Mystic Lotus

Self-Sustainable

Self-Sustainability is dedicated to the interests of Maximus & Florence.

How do you determine Water needs?

Reducing water demand

Reducing water consumption in the home is a simple and easy way to decrease water and energy bills and lessen your household’s impact on the environment.

Every household can cut down water use at low cost, often with costs recouped through water and energy savings within one year.

Six ways to minimise water use

Reduce indoor water use by choosing water efficient showers, toilets, taps and appliances.

Minimise outdoor water use by choosing plants that are appropriate for local growing conditions and by including low water use areas in the garden design through the use of indigenous plants or low water use species (see Outdoor water use).

Minimise paving of outdoor areas as this increases heat radiation and water runoff from the site.

Wash cars and bikes on the lawn to water grass at the same time.

Sweep paths and drives instead of hosing them down.

Reuse water where possible to reduce the consumption of potable water for non-potable purposes (see Wastewater reuse; Rainwater).

The WELS product rating system

The national Water Efficiency Labelling and Standards (WELS) scheme gives consumers information about the water efficiency of products.

A WELS star rating label indicates water efficiency for consumers.

The WELS scheme requires certain products sold anywhere in Australia to be registered, rated and labelled for their water efficiency in accordance with AS/NZS 6400:2005, Water efficient products: rating and labelling.

The Standard currently covers showers, dishwashers, washing machines, toilets and urinals, taps and flow controllers. The products are legally required to display the WELS label; labelling is voluntary only for flow controllers. Other products may be added to the scheme in the future.

The scheme also sets minimum water efficiency standards for washing machines and toilets.

The water efficiency rating is displayed on WELS products on a blue star water rating label. Labels for different categories of products differ slightly but all show two key pieces of information:

the WELS star rating — the stars indicate water efficiency: the more stars, the greater the water efficiency

the average water consumption per use (dishwashers, washing machines, toilets, urinals) or

the average water flow per minute (taps, showers, flow controllers).

Showers

The shower is one of the easiest and most cost effective places to decrease water use.

An inefficient showerhead can use between 15L and 25L of water every minute while an efficient WELS 3 star rated one gives a high quality shower using as little as 5L every minute. Look for the water flow rate on the label. Depending on the model you choose it is possible to get additional features such as massage and self-cleaning. Water efficient showerheads can save a two-person household at least $160 annually on household energy and water bills. The reduction in hot water means less energy is needed for water heating.

Water efficient showerheads give a high quality shower while saving water.

The environmental benefits are:

lower water use

decreased wastewater volume

fewer CO2 emissions from reduced hot water use

Toilets

There are many ways to reduce the amount of water used by your toilet:

Use the half-flush button when appropriate.

If you have a single flush toilet, engage a plumber to adjust the flush volume.

Adjust the flush volume yourself by inserting a water displacement device (purchased or a plastic bottle filled with water) into the cistern, making sure it doesn’t obstruct the mechanism. Don’t use bricks as they can crumble and stop the system working properly.

Replacing a 12L single flush toilet with a 4.5/2.2L WELS 6 star toilet in a household of four people could save more than 60,000L of water a year.

Maintaining toilets can significantly reduce household water use.

Fix leaking toilets immediately. A slow, barely visible leak can waste more than 4,000L a year. Visible, constant leaks can waste more than 96,000L.

Check for leaks by placing a couple of drops of food colouring or dye into the cistern. If colour appears in the bowl within 15 minutes without flushing, then a leak exists and the system should be repaired.

The most water efficient toilet is a waterless toilet and a range of models and types is available. They work with no odour and little maintenance while providing excellent compost (see Waterless toilets).

Taps

A tap leaking at the rate of one drip a second wastes more than 12,000L of water a year.

A number of simple measures can ensure your taps are not using more water than necessary:

Fix leaks immediately.

Don’t over-tighten taps. It can wear the washer and cause leaks.

Install a flow regulator on existing kitchen and bathroom sink taps.

Ensure that all new taps are water efficient. Check the WELS star rating. Choose 4 or 5 stars for bathroom basins and 3 or 4 stars for the kitchen sink.

Install mixer taps in showers. They can reduce the potential for scalding and save large quantities of water wasted through running the shower while trying to get a comfortable water temperature.

In basins and sinks, install separate hot and cold taps. Mixer type taps are usually left in the middle position. This means that each time the tap is run for a glass of cold water or to rinse a toothbrush, hot water is drawn off and left to cool in the pipe without ever being used.

Washing machines

The laundry is a great place to reduce water consumption and is a potential source of water for your garden. Improve the efficiency of water use in the laundry by taking these steps:

Adjust the water level on the machine, if you can, so it is appropriate for the size of load. Try to wash only full loads of laundry and use the economy cycle if you have one.

Use the suds saver function if your machine has one.

Choose cold washes to save more energy, if the wash is satisfactory.

Divert the wash water from your laundry to other uses, such as flushing the toilet or watering the garden. Check with the local council to make sure it is allowed and installed to comply with regulations (see Wastewater reuse).

Purchase a water efficient washer with a high WELS star rating. Most front loaders are efficient and some efficient top loaders are now on the market. A high star rated model saves 50L or more with every load — and uses less detergent (the big money saver).

Dishwashers

Dishwashers are also WELS star rated and the most efficient models use less than half the water of an older model. The highest star rated dishwashers can use less than 1L per place setting — that’s less water than many people use washing dishes by hand.

Try these simple ways to use water more efficiently when washing dishes:

Avoid rinsing before washing. Scrape food remains off dishes and dispose of them in the compost or garbage bin rather than rinsing them away.

Always use a plug in the sink rather than letting the tap run continuously.

Try to fully load the dishwasher before using it and use the economy cycle if you have one.

Other water saving tips

In-sink waste disposal units use water when operating and also mix wastewater with food scraps. From an environmental viewpoint, well controlled and managed home composting is the most favoured option for food waste disposal (CRC Waste Management and Pollution Control 2000).

Storage water heaters release some water through a pressure release valve when they are heating water. Have a professional check the release valves on your water heater. The amount of water used may be minimised by setting the release rate to the minimum recommended by the manufacturer (see Hot water service).

Evaporative air conditioners drain off some water while in use to reduce the build-up of impurities. Ensure that the drain-off rate is set to the minimum required for the air conditioner to work with your water supply. Make sure the air conditioner is turned off when you go on holidays (see Heating and cooling).

Rainwater

Rainwater is a valuable natural resource that has been collected by Australian households for domestic use since colonial times.

Opportunities for rainwater collection and use vary with location. Urban households typically have a connection to a reticulated, treated (mains) water supply but can significantly lower mains water usage by installing a rainwater harvesting system.

Most rural households have to source all their water on their property, and rainwater often provides a better quality household supply than river, bore or dam water.

Benefits

Using rainwater can reduce water bills, provide an alternative supply during water restrictions and help maintain a green, healthy garden. Depending on tank size and climate, mains water use can be reduced by up to 100%. This in turn can help:

reduce the need for new dams or desalination plants

protect remaining environmental flows in rivers

reduce infrastructure operating costs

Rainwater harvesting also decreases stormwater runoff, thereby helping to reduce local flooding and scouring of creeks.

Costs

Apart from the up-front cost, there are ongoing electricity costs if a pump is part of the system, and ongoing maintenance for the homeowner.

Rebates are available from Australian, state, territory and local governments. Go to www.yourenergysavings.gov.au to check the Australian, state or territory government rebates available for your property, and contact your council directly to find out if they offer rebates. The rebate amount usually depends on the tank volume and the types of household uses for the water.

Rainwater use

Rainwater collected from a well-designed, well-maintained system can be suitable for all domestic uses. The more uses, the greater the savings in mains water. Bear in mind that the amount of water used for drinking and cooking is relatively small, and that state and territory health departments recommend using the public reticulated water supply for drinking and cooking because it is filtered, disinfected and, generally, fluoridated. For more information, consult your state or territory health department.

Different end uses each require a different rainwater quality.

Health and safety

Rainwater tanks can impact adversely on human health in two main ways:

indirectly, by providing a breeding place for disease-carrying mosquitoes

directly, if the rainwater is consumed by the household, or others if it flows back into a municipal reticulated water supply. Pathogens such as Cryptosporidium and Giardia may be present in rainwater, and in urban areas, lead and other compounds pose a risk of chemical contamination. The absence of fluoride in rainwater should also be considered for children in the household.

Prevent mosquito breeding in the tank

To avoid creating a mosquito breeding habitat, ensure tank inlets and overflows are properly screened to exclude mosquitoes.

Drinking rainwater

If your rainwater is to be used for human consumption, the system must be designed, operated and maintained to ensure the water quality is suitable. Disinfecting the water before consumption should still be considered for those whose immune system is compromised.

Backflow prevention

If rainwater and mains water are interconnected (such as for back-up), the mains water must be isolated from the rainwater system by a suitable backflow prevention device or a visible air gap, as required by the Plumbing Code of Australia. Most mains switchover devices already incorporate backflow prevention suitable for use with an above-ground tank.

If mains water is interconnected with rainwater from an underground tank, a testable backflow prevention device must be fitted on the mains water supply to the house. It normally needs to be tested annually.

Rainwater harvesting system checklists

Use these lists to guide the design of a rainwater system suitable for your property and planned rainwater uses. A rainwater harvesting system has the following components:

roof and gutters

collection system, including leaf-shedding rain-heads and first flush diverters

tank

supply system, possibly including pump and filters

The components of a rainwater harvesting system.

A ‘charged line’ system is needed if the pipe does not slope downwards along its length to the rainwater tank. The pipe can go down, often underground, and then up again, usually at the tank. The term ‘charge’ comes from the water being pushed up the pipe by the pressure of the water in the pipe.

In a charged line rainwater system the water is pushed into the tank by water pressure in the pipe.

Roof and gutters

Rainwater can be collected from most roof types, depending on the quality of rainwater required.

For garden or lawn irrigation:

collect from any roof material except unsealed asbestos

ensure all gutters fall towards the outlets

preferably fit an effective leaf screen to the gutters

use gutter outlets that fit to the underside of the gutter

For all other uses, also:

prevent vegetation from overhanging the roof

clean the roof and gutters before installing the system

fit a good quality leaf screen to gutters or use a leaf-shedding gutter

For drinking water, also avoid collecting rainwater:

from sections of roof containing lead flashing or asbestos sheeting, and from roofs painted with pre-1980 paint — if they cannot be avoided, seal properly by preparing the surface and painting with a suitable potable-quality roof sealant, and do not collect rainwater from the first few rainfall events after sealing

in areas where airborne toxins are present from nearby activities such as crop-dusting and chemical processing

Leaf-shedding rain-heads

If no leaf screen is fitted to gutters, fit leaf-shedding rain-heads to the downpipes. These devices employ a sloping screen to intercept leaves and reduce excessive leaf build-up in first flush diverters and tank inlet strainer baskets. They are essential if the tank has no inlet strainer (e.g. a bladder tank). Install the rain-heads higher than the tank inlet but at a height that can be easily accessed for maintenance.

Gutter leaf screens keep leaves out of the rainwater collection system.

Leaf-shedding rain-heads intercept leaves and reduce excessive leaf build-up.

First flush diverters

The first rain after a dry spell washes some of the accumulated dust and bird droppings off your roof and into your rainwater tank, accumulating as sediment in the bottom of the tank and lessening the quality of the water. First flush diverters intercept the first roof runoff and prevent it from entering your rainwater tank, in one of two main ways:

storing the first rainwater runoff and slowly draining it (e.g. to the garden)

diverting the first rainwater runoff and then closing

First flush diverters are typically sized to divert about 10L per 50m² of roof plan area. A diverter may be required by local government regulation.

First flush diverters should be installed for all drinking water systems and are beneficial for systems supplying other internal uses. For garden irrigation supply, their main benefit would be the reduced need for desludging the tank.

Installation details include ensuring:

the first flush diverter is securely mounted

there is enough clearance to easily remove parts that need cleaning

Rainwater tanks

Choose a rainwater tank that suits your needs.

Tank size

When deciding the best size for your tank consider:

uses to be supplied - maximise the uses of rainwater to get the best value from your rainwater tank

average amount of water consumed by these uses - available from your water supplier or try the calculator on the Hunter Water website hunterwater.com.au

local rainfall pattern - find the annual rainfall in your area on www.bom.gov.au — in areas with highly variable rainfall, much bigger tanks are required for the same supply of rainwater

area of roof draining to the tank - 1mm of rainfall on 1m² of roof area = 1L of rainwater

security of water supply you desire - a larger tank volume leaves fewer periods without rainwater

Approximate tank sizes for a four person household with mains water and evenly spread rainfall is 20,000L.

Where average rainfall is highly seasonal or no mains water is available, much larger tanks are typically required.

Use the Alternative Technology Association Tankulator at http://tankulator.ata.org.au to help evaluate the effect of different tank sizes on water savings.

Tank materials

Common tank materials include polyethylene, fibreglass, concrete and steel.

Steel tanks are strong and can be made to a custom size. They are available in stainless, Zincalume^® or Colorbond^® steel. Smaller tanks are prefabricated; tanks over 30kL are usually assembled on site. Prefabricated steel tanks are usually coated internally and under the base with a polymer film to prevent corrosion. The polymer lining commonly used in Australia should be protected from direct sunlight as it is not UV stabilised. Suppliers generally require steel tanks to be installed on a concrete slab, pavers or a stand.

Plastic tanks are durable, relatively lightweight and relatively inexpensive. They can be buried partially or completely if designed for underground installation.

Concrete tanks are strong and have the best bushfire resistance. They are available prefabricated in above-ground or underground models or can be constructed on site to meet specific site and homeowner requirements.

Tank types

Round, above-ground rainwater tanks are usually the cheapest type of prefabricated tank per litre of volume. However, in recent years a range of innovative systems has been developed to provide rainwater storage capacity where space is limited.

Slimline tanks may be installed along a fence line or at the side of your house (check local government planning regulations). They usually need a properly formed concrete slab for support, depending how tall they are relative to their width.

Slimline tanks installed along a wall save space while saving water.

Storage walls are very slim modular slimline tanks (typically plastic) that lock together to fit into tight spaces. They are generally the most expensive tank type.

Storage walls fit into tight spaces.

Underground tanks save on space and usually have greater catchment potential than above-ground tanks. However, this option requires excavation and if the water is to be used inside the house, the Plumbing Code of Australia also requires that a testable backflow prevention device is fitted on any mains water supply to the house and tested annually. Underground tanks cost a similar amount to slimline tanks (excluding installation).

Underground tanks can capture all runoff water and save space.

Bladders are sealed, flexible sacks that are suitable for subfloor spaces with as little as 600mm height clearance. Their installation is more technically involved than a standard tank but they can be especially good for renovations where space is limited. Underfloor bladders may be able to collect from a larger roof catchment than above-ground tanks if inlet pipes can be routed under the floor from downpipes on both sides of the house. Bladder tanks save on outdoor space and cost a similar amount to slimline tanks.

Bladder tanks can fit under a floor with as little as 600mm clearance.

Tank details

For water quality, ease of maintenance and public health:

ensure the inlet strainer is mosquito proof and can be easily removed for cleaning

fit a vector-proof flap valve to overflow if open to the air

fit a separate valve to the bottom of the tank to allow easier desludging

For drinking water, also:

fit the outlet 100mm above the bottom of the tank or use a floating outlet

if possible, provide shade for the tank

Gravity feed

Gravity can be a reliable, silent way to supply rainwater without external power. The tank can be placed on a stand, or a garden tap fitted near the bottom of a tank to provide sufficient pressure to fill a watering can or a pool, or slowly water a lower garden by hose. If the rainwater collection area and tank are more than 15m higher than the house, gravity pressure can be sufficient for all domestic uses. Lower, the pressure may not be enough for some fixtures and appliances including most modern mixer taps, washing machines and ‘instant’ gas heaters.

Header tank

Household systems can incorporate a small header tank located at a higher elevation, perhaps at roof height. A low-powered pump is used to transfer the water from the main rainwater tank to the header tank. The rainwater can then be delivered by gravity to the household. These systems can be much more efficient than mains pressure pump systems. However, water pressure will be low from a header tank less than 15m above the water outlet. The water supply pipes in the house also need to be sized to suit low pressure supply.

Pump systems

Pressure pumps

A suitable pressure pump delivers water at or near mains pressure, to make full use of your rainwater. Rainwater pumps are either submersible or free-standing.

A submersible pump in the rainwater tank saves space and emits much less pump noise. A free-standing pump is often cheaper and available in a greater range of pumping capacities, but needs a weather protected spot near the tank and an enclosure to limit pump noise.

A submersible pump can be fitted in the rainwater tank.

Select a pump that delivers the expected flow rate while maintaining enough pressure at the most critical water supply point. Consider:

the required minimum delivery pressure

friction losses due to pipe, filters and controllers

the pressure needed to lift the water to the height of the most critical water fixture

Pump suppliers and hydraulic consultants can help with correct selection of the pump.

Free-standing rainwater pressure supply pumps are available in a range of capacities.

Pump controllers

A rainwater pump is typically supplied with a suitable controller to switch it on and off as required in response to the water flow. For outdoor water uses the controller is often mounted on the pump.

For whole-of-house rainwater supplies, a variable speed pump delivers a more even pressure at the expense of energy efficiency.

The most energy efficient pressure pump control system incorporates a pressure accumulator tank and a mechanical pressure switch.

An efficient pump control system incorporates a pressure accumulator tank with mechanical switch.

Mains switch-over devices

Some controllers also switch the supply from rainwater to mains water when the rainwater runs out. This type of controller is commonly used for rainwater supply to toilets, washing machines and other internal uses where a mains water supply is also available. They typically incorporate a float switch in the tank. It is good practice to place a mesh inline strainer between the pump and the controller to protect this type of controller from being damaged by foreign objects.

Filters

It is beneficial to filter the rainwater supply to some fixtures.

Consider the following when incorporating filters into the design:

Ensure that the filter housing is accessible and that shut-off valves are installed so the water won’t drain out of the pipework. Pleated sediment filters must be changed annually if they are part of a drinking water supply. Ceramic filters need to be removed for cleaning when the flow rate becomes too low.

Filters reduce pressure and flow, and must be sized correctly and allow for the pressure drop in the pump selection.

Consult filter suppliers for advice on a suitable filter for the particular quality and flow rate required.

System maintenance

Regular maintenance is needed to ensure that your rainwater is safe for all requirements around the home, particularly for drinking.

Design and construct the system so that the maintenance schedule can be carried out.

Monthly:

Check and clean tank inlet screens, outlet screens and leaf-shedding rain-heads.

Check and clean the first flush diverter.

Annually:

Check roofs and gutters and remove debris.

Check filters annually and replace if necessary.

Remove overhanging vegetation where possible.

3–5 yearly:

Desludge your tank.

In the longer term, rainwater pumps typically need servicing or replacing after approximately 10 years of use.

Wastewater reuse

On-site wastewater reuse can reduce water use in both urban and rural households. At present, most homes use potable (drinkable) water for practically everything in the house and garden.

We are literally flushing our drinking water down the toilet!

The articles Reducing water demand, Rainwater and Outdoor water use also have information on reducing potable water use.

Opportunities to reuse wastewater and regulation of its treatment vary according to where you live. Urban households typically have a connection to a centralised, or reticulated, sewage system, whereas rural households manage their wastewater on site. Check with your local council or state health authority for advice on the regulations in your area.

Two types of wastewater are created in a home: greywater and blackwater.

Greywater is wastewater from non-toilet plumbing fixtures such as showers, basins and taps.

Blackwater is water that has been mixed with waste from the toilet. Because of the potential for contamination by pathogens and grease, water from kitchens and dishwashers should be excluded from greywater and considered as blackwater.

Each wastewater type must be treated differently and can be used in various ways. Greywater is ideal for garden watering, with the appropriate precautions, such as using low or no sodium and phosphorus products and applying the water below the surface. Appropriately treated greywater can also be reused indoors for toilet flushing and clothes washing, both significant water consumers.

Blackwater requires biological or chemical treatment and disinfection before reuse. For single dwellings, treated and disinfected blackwater can be used only outdoors, and often only for subsurface irrigation. Check with your local council or state health department on local requirements.

A wastewater reuse system.

Advantages of reuse

By using wastewater as a resource rather than a waste product you can:

reduce water bills

use fewer water resources

irrigate the garden during drought or water restrictions

cut down the amount of pollution going into waterways

help save money on new infrastructure for water supplies and wastewater treatment

decrease demand on infrastructure for sewage transport, treatment and disposal, allowing it to work better and last longer

Disadvantages of reuse

The disadvantages of reusing wastewater also need to be considered. Currently, the main disadvantage for most households is the financial cost of installing and maintaining a reuse system. The attractiveness of the investment would depend on:

the extent of centralised wastewater treatment services available

the price of water in your area (urban) or scarcity of water (rural)

whether you are replacing an existing system or starting from scratch

the length of time you intend to live in your current house

the type of system — annual operating and maintenance costs vary between systems

whether a restriction free, reliable water supply is valuable to you — wastewater reuse is often a much more reliable secondary source of water than common rainwater tank installations (see Rainwater).

If your house is frequently unoccupied for a fortnight or more, for example a holiday home, select carefully to find a reuse system that can cope with intermittent use. Most systems that include biological treatment do not function properly if used intermittently.

Calculating wastewater volume

The table indicates the approximate amount of wastewater produced by one person each day in an average home with Water Efficiency Labelling and Standards (WELS) scheme 3 star rated fixtures (see Reducing water demand).

Reuse water quality

The quality of reused water depends on the treatment system, the water’s previous use and the chemicals used in the home. A number of things can simplify treatment requirements.

Many different indoor locations generate wastewater.

For greywater:

Minimise the use of cleaning chemicals. Use natural cleaning products where possible.

Use low or no sodium laundry detergents, soaps and shampoos.

Use a lint filter. Clean and replace as necessary to ensure water can flow through it easily.

Do not dispose of household chemicals down the sink. Contact your local council or water authority for information on chemical collection services.

For blackwater:

Minimise the use of cleaning chemicals. Use natural cleaning products where possible.

Do not dispose of household chemicals down the toilet.

Use a sink strainer in the kitchen to help prevent food scraps and other solid material from entering your wastewater.

Wastewater reuse in urban areas

Consider reusing wastewater in an urban, sewered area if:

you wish to further reduce water use beyond already implemented efficiency measures for indoor and outdoor water use (see Reducing water demand; Outdoor water use)

water supplies in your area are often limited by frequent restrictions or droughts

your large garden needs to be watered often or would not survive extended water restrictions

Remember to check with your local council or water authority before you reuse wastewater, as standards and permission requirements vary.

Wastewater reuse in rural areas

Rural households typically have greater scope for reusing wastewater because:

without a centralised treatment service, investment in an on-site wastewater treatment system is a necessity

installing a reuse system in a new house, or adapting an existing treatment system to allow reuse, may not incur significant additional expenditure

water supply may be restricted, placing a premium on using water resources in the most efficient manner (see Reducing water demand; Rainwater)

large blocks of land in rural areas allow more scope for on-site disposal of wastewater

NOTE: The septic tank system, the most prevalent on-site wastewater treatment system in rural Australia, does not actively treat wastewater to remove disease-causing pathogens. Effluent from a septic tank should be disposed of underground at soil depths greater than 300mm.

Reusing wastewater outdoors

Reusing wastewater outdoors can reduce a household’s potable water use by 30–50% (see Outdoor water use).

However, a number of precautions need to be taken to ensure it is safe and environmentally sound.

Avoid watering vegetables with reuse water if they are to be eaten raw. There is a chance that some pathogenic organisms may still be present even after treatment.

To maintain the health of your garden, the level of reuse of wastewater needs to be balanced with the amount of water, solids and nutrients that the plants and soil in the garden can absorb.

If excess wastewater is applied:

excess nutrients may run off or leach through the soil to enter waterways, contributing to algal blooms and other water quality problems

soils and plants may become waterlogged and inhibit plant growth

soils can become physically clogged with organic and suspended material or damaged by salts in the wastewater

salinity may increase in problem areas when greywater contributes to rising watertables

Avoid these problems by:

planning your garden carefully (see Outdoor water use; Landscaping and garden design)

using phosphate-free and salt-free liquid or environmentally friendly detergents

pre-filtering to remove solids

Adjust the amount of wastewater to conditions in the garden. Do not irrigate if the soil is already saturated (see ‘Wet weather storage’ below).

Greywater treatment for outdoor use

Greywater can be reused in gardens with little or no treatment. Subsurface irrigation systems — slotted drainage pipe or special driplines — spread water evenly around the garden and are safer for untreated greywater.

Simple greywater subsurface reuse.

Slotted drainage pipes and greywater driplines spread greywater evenly around the garden.

Blackwater treatment systems for outdoor reuse

Outdoors is the only place where treated and disinfected blackwater can be safely reused. There are many different types of blackwater treatment systems suitable for outdoor use. Contact your local council for a list of accredited treatment systems for your area.

Currently the most common wastewater treatment and reuse system in Australia is the aerated wastewater treatment system and many commercial models are available in all states. After the wastewater solids have settled, the effluent is aerated to assist bacterial breakdown of organic matter, followed by a further stage of disinfection, usually using chlorine pellets.

On-site wastewater treatment systems using microfiltration are now available for domestic use. These systems require no chemicals but do need energy.

Some treatment systems use worms and microbes, and little energy and no chemicals, to treat all household wastewater. They produce effluent suitable for subsurface irrigation and compost as a by-product.

There are many commercial models of aerated wastewater treatment systems available in Australia.

Wet weather storage

Wastewater reused in the garden needs to be disposed of or stored when it is not required during periods of high rainfall.

If storage is not an option, excess wastewater can be directed to a sewer in an urban area. In rural areas with enough space, subsurface disposal to a trench in the garden is recommended.

Storage maximises the usefulness of wastewater but it needs to be treated and disinfected before storage.

Storage requirements depend on:

climate

household demand for reuse water

presence/size of disposal area

maximum daily wastewater output

Reusing greywater indoors

In homes with access to a reliable rainwater supply, it is generally more economical just to use greywater outdoors and rainwater indoors. However, if you are unable to collect enough rainwater, treated greywater can reliably reduce indoor water use.

Treated greywater can be reused for toilet flushing and clothes washing, two of a household’s biggest users of water.

Appropriately treated greywater can be reused for toilet flushing and clothes washing, which are two of the biggest users of water in an average household (see Reducing water demand).

Reusing treated greywater for toilet flushing can save approximately 50L of potable water in an average household every day. Reusing treated greywater in a clothes washer can save approximately 90L of potable water in an average household every day.

A greywater treatment and disinfection system, approved in your state, must be installed to reuse greywater indoors for toilet flushing and clothes washing. These systems give a suitable level of treatment and meet local regulations.

NOTE: Wastewater from the kitchen sink and dishwasher can be classed as greywater but requires more complex treatment before reuse. Many states in Australia do not allow water from kitchens to be included in greywater for reuse, and permit greywater only from showers, hand basins and laundries.

Greywater can be directly diverted from the shower or bathroom sink for toilet flushing as long as it is used immediately and not stored for more than 24 hours before reuse or disposal to sewer. It requires coarse filtration.

Precautions

Greywater must be treated and disinfected before storage and general reuse because it:

can contain significant numbers of pathogens that spread disease

begins to turn septic and smell if stored for longer than 24 hours untreated

Dissolved organic material in greywater reused for washing clothes may discolour clothing. An activated carbon filter can overcome this problem.

Treatment systems for indoor greywater reuse

A number of proprietary on-site greywater treatment systems are available for purchase in Australia. Your council or state health department can advise which are accredited for use in your area.

The treatment processes may employ biological, chemical or mechanical means. The qualities of treated water they produce can vary considerably, as can their initial cost and energy consumption.

With council approval, it is possible to build your own biological treatment system for greywater treatment. ‘References and additional reading’ at the end of this article has more details.

Biological greywater treatment generally consists of several steps:

Coarse filtration to remove large particles, including hair, and prevent clogging. It can be as simple as a waterproof box and a filter bag or stocking attached with rubber bands. Check the stocking or bag frequently and replace it when full.

Fine filtration and biological treatment, using a sand filter and reed bed combination. Microbes in the sand break down organic matter in the water and the reeds take up nutrients. The basic structure is a waterproof box filled with coarse sand laid over a gravel bed. It is designed so that greywater percolates either vertically or horizontally through the media.

Any greywater reused indoors must be disinfected. All disinfection systems require frequent maintenance. Chlorine, although the most common disinfectant, has been found to have adverse environmental impacts. Alternatives such as UV or ozone disinfection should be used where possible but they do require electric power to operate. UV sterilisers disinfect the water as it passes through them and use about 20–40W of electric power depending on the water flow rate they can treat. Ozone systems use about 50W of power and operate for about 30 minutes six to eight times a day depending on water usage.

Systems for treating greywater can be quite simple to build.

UV sterilisers disinfect water as it passes through them.

Stormwater

Stormwater is the water draining off a site from the rain that falls on the roof and land, and everything it carries with it. The soil, organic matter, litter, fertilisers from gardens and oil residues from driveways it carries can pollute downstream waterways.

Rainwater refers only to the rain that falls on the roof, which is usually cleaner. However, stormwater can be a valuable resource. Reusing stormwater can save potable water and reduce downstream environmental impacts.

In urban areas stormwater is generated by rain runoff from roofs, roads, driveways, footpaths and other impervious or hard surfaces. In Australia the stormwater system is separate from the sewer system. Unlike sewage, stormwater is generally not treated before being discharged to waterways and the sea.

Poorly managed stormwater can cause problems on and off site through erosion and the transportation of nutrients, chemical pollutants, litter and sediments to waterways. Well-managed stormwater can replace imported water for uses where high quality water is not required, such as garden watering.

A homeowner can take simple steps to manage stormwater and reduce its environmental impact.

Take some simple steps to better manage stormwater and reduce the environmental impact of your home.

Avoid cut and fill on your block when preparing the building foundations. Attempt to maintain the existing topography and drainage pattern.

Retain vegetation, particularly deep-rooted trees. They lower the watertable, bind the soil, filter nutrients, decrease runoff velocities, capture sediment and reduce the potential for dryland salinity.

Reduce erosion potential on site during building works by minimising the time that land is left in an exposed, unstable condition. Employ sediment traps and divert ‘clean’ stormwater around the disturbed site (see Sediment control).

Minimise the area of impervious surfaces such as paved areas, roofs and concrete driveways.

Grade impervious surfaces, such as driveways, during construction to drain to vegetated areas.

A stormwater site plan can help reduce stormwater runoff from the site.

Detain stormwater on your block where practicable through use of permeable paving, pebble paths, infiltration trenches, soakwells, lawns, garden areas and swales.

Harvest and store roof water for use (see Rainwater).

Take care with the substances used on your land as they can end up in the stormwater. Don’t overuse fertilisers, herbicides and pesticides; follow the manufacturer’s instructions on the amount and frequency of application. Look for organic alternatives.

Water sensitive urban design slows stormwater runoff and improves filtration and infiltration.

Avoid using solvent-based paints. After using water-based paints, clean brushes and equipment on a lawn area to trap contaminants before they reach waterways. Plant-based paints are the most environmentally benign.

Visit a car wash that recycles wash water. If this is not an option wash your car on the lawn or on an area that drains to lawn. The nutrients (mostly phosphates and nitrates) in the detergent fertilise the lawn instead of degrading waterways. Note that many native plants do not tolerate detergents.

Do not build on floodplains as the land may be periodically subject to inundation and may have a high watertable. Councils can advise on the 1 in 100 year flood level.

The traditional approach

The traditional stormwater management response relied on conveyancing. Water was conveyed by a pipe or channel from a collection area (e.g. house and street) to a discharge point (e.g. the nearest ocean, creek, river or lake). The conveyancing system sought to remove the most water (high quantity) from a site in the shortest time possible (high velocity). Large, impervious paved areas and big pipes are typical of conveyancing.

The traditional system of conveyancing is highly effective in reducing stormwater nuisance and flooding on site, unless the pipes get blocked. But it merely transfers the problem to the other end of the pipe and ultimately upsets local water balance. Stormwater is carried rapidly with its suspended litter, oil, sediment and nutrients, and dumped into a receiving waterbody that then becomes flooded and temporarily polluted because all the stormwater arrives at one time.

Water sensitive urban design

Water sensitive urban design (WSUD) seeks to imitate the natural water balance on site before the land is built on. It slows stormwater runoff to gain natural filtration, on-site detention and infiltration. The water eventually reaches the river, lake or ocean but has been cleaned and filtered by the soil and used by plants before it gets there.

Water sensitive urban design slows stormwater runoff to gain natural filtration, on-site detention and infiltration.

The objective is to minimise impervious surfaces so that the least water flows off-site into the stormwater system. At the scale of the individual household, options such as permeable paving on driveways and footpaths, garden beds designed for infiltration (raingardens), lawns and vegetation, swales and soakwells can detain stormwater and increase percolation into the soil.

In some cases it may be advisable to place perforated pipes beneath infiltration areas to direct excess stormwater to the stormwater system. See ‘References and additional reading’ for publications on options and possible designs.

The improved aesthetics and comfort associated with more vegetation also improve habitat for native wildlife and make the area cooler in summer. It reduces the need for garden watering and decreases water bills. Also reduced are erosion and the downstream effects of stormwater pollution on nearby rivers, lakes or the ocean.

Creek beds can add aesthetic appeal even when dry.

Flood mitigation

Many new houses have on-site detention facilities constructed as part of their home drainage system. The facilities, usually large concrete basins built beneath driveways, are designed to capture stormwater runoff from a residential lot and hold it a little longer to reduce the impact of downstream flooding. The stored water drains slowly through a small opening near the base of the tank to the stormwater system. When many properties in flood prone areas have these detention systems, the downstream flood ‘peak’ during large storms is reduced and flood damage minimised. Local councils set regulations for on-site detention systems; check with your local council to see if your new home needs one.

On-site detention facilities capture stormwater runoff from a residential lot and hold it a little longer to reduce the impact of downstream flooding.

Things to consider

WSUD is applicable on all sites but the degree of application varies according to the site’s opportunities and constraints. All sites should be able to maximise permeable surfaces such as garden beds, lawns, porous paving and paths.

Before installing subsurface units such as soakwells and infiltration trenches, consider the following matters for your site:

Soil type - Check the soil type, which affects the efficiency of some WSUD solutions. Sandy soils are excellent for infiltration but clay soils tend to become waterlogged. For example, water sensitive design in heavy clay soils may need to be supplemented with traditional conveyancing methods.

Soil depth - Ensure that the soil has sufficient depth. Areas with shallow soil underlain by impervious rock such as granite, shale or limestone may impede infiltration and may require some stormwater pipes to remove water for discharge off-site.

Groundwater - Determine the depth to groundwater. A high groundwater table may reduce the effectiveness of infiltration methods during storms.

Slope - Ensure that the stormwater design accounts for the terrain. Severe slopes increase runoff velocities.

Regulations - Check with your local council before employing WSUD solutions. Some components of WSUD may conflict with local government drainage regulations.

Other design suggestions

Ensure there are no illegal cross-connections of sewer and stormwater drains, i.e. the stormwater drain discharging into the sewer system. They can cause sewage overflows on your property during heavy rain.

Prevent rain from washing sediment (e.g. sand, soil) into stormwater with a roof, tarpaulin or awning.

Divert stormwater from driveways, paths and other impervious surfaces to vegetated areas to catch, filter and infiltrate water rather than directing water to the stormwater system.

Divert excess overflow from hard surfaces such as driveways, patios and roofs through downpipes to a raingarden to filter water before it enters local waterways through the stormwater system.

Measures to promote water conservation

Appropriate landscaping (see Outdoor water use; Landscaping and garden design)

Water harvesting (see Rainwater)

Stormwater and greywater recycling (see Wastewater reuse)

Environmental benefits

The downstream environmental benefits of reduced stormwater pollution are:

cleaner rivers, lakes and beaches that are safer for swimming

reduced flooding

councils spending less money emptying stormwater traps

a healthier environment for plants and animals

Outdoor water use

Around 40% of household water is typically used outdoors.

There are many easy ways to reduce outdoor water use, save money, time and effort, and benefit the natural environment.

Garden design

Paved areas increase heat radiation and water runoff from the site. Minimise the use of paving in outdoor areas.

Group plants with similar water needs together. Divide plants into high, medium and low water-use zones in your garden (see Landscaping and garden design).

Grow high water-use plants together.

Examples of plants for water-use zones

High water-use - Lawns, most vegetables, fruit trees, exotic shrubs like azaleas and camellias, flowering herbaceous annuals and many bulbs

Medium water-use - Hardy vegetables like pumpkins and potatoes, hardy fruit trees and vines like nut trees and grapes, many herbs, some exotic shrubs, most grey or hairy leafed (tomentose) plants, roses and daisies

Low water-use - Hardy vegetables like pumpkins and potatoes, hardy fruit trees and vines like nut trees and grapes, many herbs, some exotic shrubs, most grey or hairy leafed (tomentose) plants, roses and daisies

Plant trees to create natural shade and windbreaks to reduce evaporation. Locate high water-use plants in areas where they are sheltered from drying winds and strong sunlight.

Where possible, use alternative water sources, such as rainwater or greywater, for high water-use plants.

Use alternative water sources, such as rainwater or greywater, for high water-use plants.

Group plants with similar water needs together.

Soil improvement

Soil types and water availability

Water holding capacity is determined by the texture of the soil and levels of organic matter. The greater particle surface area of finer soils gives them a greater capacity to hold water.

The three main soil types are sand, loam and clay. Sandy soils drain rapidly; clay soils hold water but make it difficult for many plants to grow; loam soils are between the two. A soil with plenty of organic matter and a mixture of fine and coarse particles that form into small composite particles (called ‘peds’) is ideal.

Hardy, deep rooted plants can help break up poor soils and adding composted organic matter encourages microbial activity and worms to improve soil condition and moisture retention.

Soil testing

A simple test to identify soil type is to take a handful of soil from the garden and add just enough water to mould it into a ball. Test soil from various sites and from different depths in the garden.

Sandy soils crumble and don’t form a ball. They are light coloured, have little or no smell. Water drains away rapidly and they are low in nutrients.

Loam soils form a ball that is friable, usually brown with a pleasantly ‘earthy’ smell. They hold and drain water well and provide good levels of nutrients. Loams are best for plants.

Clay soils ball easily and range in colour from white to red or dark brown. Clay has fine, dense particles that do not allow water to soak in easily, and become hard and resist water when dry. They may be high in nutrients that are unavailable to most plants.

Improving soil

Add organic material. The water and nutrient holding capacity of sand and clay soils can be improved by the addition of organic matter such as manure, leaf mould, worm farm castings and compost. Dig in to a depth of 15–20cm.

Gypsum and sand added to clay soils help break the clay into clumps, and improve air space and drainage. Add gypsum at the rate of 0.5–1.0kg/m2. A combination of gypsum, sand and composted organic matter produces the best results in clay soils.

Chemical additives often produce a quick fix but may have adverse environmental impacts in the medium or long term. Natural methods are better. Make use of organic food waste by using a home composting system or worm farm to supply natural soil conditioner and fertiliser — and reduce waste going to landfill.

Water crystals and soil wetting agents can increase soil moisture for use by plants. Soil wetting agents allow water to penetrate dry soil surfaces and prevent runoff; water crystals help store water in the soil.

Lawns

Reduce lawn area

Lawns consume up to 90% of water and most of the energy used in most gardens. They also take the most time and money to maintain. Lawns need mowing, weeding, edging and fertilising, and equipment requires fuel and maintenance.

Reducing lawn area is the easiest way to save water. Create garden beds or spread mulch in areas used infrequently or where grass grows poorly.

Replace lawn areas with porous paving, pebbles or drought-tolerant ground covers such as prostrate grevilleas, snake vine (Hibbertia scandens) or myoporum. Seek advice at your local plant nursery.

Vegetable gardens produce low-cost food for the household and save on ‘food miles’.

Reduce water use on lawns

Different grass types have different watering needs. Select a turf that needs less water such as couch, Queensland blue couch, buffalo, Nioaka and Nathus Green (Sporobolus virginicus), tall fescues and carpet grass. Many blends and species are region specific. Ask your local plant nursery for the most suitable low water species for your climate and soil type.

Do not ‘scalp’ the lawn. Set your mower to cut 4cm or higher. This encourages a deeper root system and the longer grass blades shade the soil, reducing evaporation.

Water only when the lawn is showing signs of stress. Long, slow soakings that allow water to penetrate to a depth of about 15cm encourage a deeper, more hardy root system.

A lightly fertilised lawn uses up to 30% less water than an unfertilised lawn of the same grass type. A diluted spray of the liquid drained from your composting worm farm (or purchased from a commercial vermiculture operation) is ideal fertiliser. It returns your waste to the soil and plants.

Plant selection

Select plants that suit the soil and garden conditions. Local indigenous plants have evolved to handle local conditions. Many other Australian native plants have evolved to cope with very little water.

Careful plant selection can make an interesting and attractive low water-use garden.

Some exotics from South Africa, California and the Mediterranean also cope well with limited water. But that may also mean they have the potential to become environmental weeds. Check with your local natural resources or catchment board particularly in outer urban or country zones and near conservation areas.

Avoid changing gardens during summer when more moisture is lost from disturbed soils and it is difficult for new plants or lawns to survive.

Explore your neighbourhood to discover what appears to grow well in your area. Take note of street trees, which are rarely watered or maintained.

Incorporating native plants into the garden provides habitat and food for birds and insects. They, in turn, can aid in pest control and pollination.

Mulching

Mulching is an essential element of a water-efficient garden. Mulching around plants saves water by preventing evaporation and reducing runoff.

Mulching limits weed growth and can improve soil conditions (depending on the type of mulch).

Mulch can be in the form of leaves and grass clippings, sawdust, rocks and gravel, straw and other crop residues, bark and woodchips. Coarse mulch is excellent for reducing weeds and keeping soil cool but it won’t improve the soil. Some nitrogen-rich fertilisers may need to be added before the mulch is laid. Medium and fine mulch are also good for limiting weed growth but can wear faster over time. This can be prevented by less frequent watering.

Before mulching, clear weeds, break up the soil crust and water the area. Spread mulch evenly to a depth of 7–10cm. If you are using fine mulch like sawdust then a thin layer of around 2.5cm is sufficient. Reapply mulch at least once a year, or as it breaks down. Do not allow organic mulch to touch woody plant stems and trunks or it may cause collar rot and kill the plant.

Mulch reduces evaporation, limits weed growth and can improve soil condition.

Watering

Water early in the morning or evening as this allows water to penetrate before it evaporates. Early morning watering allows plants to use the water throughout the day.

Less frequent, deep soakings train plant roots to grow down into the soil and increase the drought tolerance of plants. Water the roots, not the leaves. Water on the leaves evaporates easily and can lead to scorching.

Controlling weeds reduces competition for water with your plants.

Occasional deep soakings train plant roots to grow down into the soil and increase drought tolerance.

Ideally, fertilise plants with organic liquid fertiliser or compost. Dry fertilisers take up some water from the soil and can raise salt levels.

Hand-held watering could be more efficient than a poorly designed automatic watering system.

Water saving equipment and products

Install alternative water supplies such rainwater tanks and greywater systems (see Wastewater reuse). Generally speaking most water is used internally in toilet flushing, and in laundries, showers and baths, which can be used as greywater for garden irrigation.

A home incorporating whole-of-house water design collects rainwater to use internally and uses it a second time for greywater irrigation.

Poorly designed and inefficient automatic irrigation systems may use more water than hand-held hoses and sprinklers. Automatic systems set to turn on regardless of weather conditions and soil moisture content waste water. Systems not adjusted to seasonal needs may deliver water too fast, resulting in runoff, or supply more water than plants require.

Install soil moisture sensors that trigger cut-off switches when it rains and adjust watering duration according to soil moisture levels.

Drip irrigation is the most efficient system. It delivers water to the roots of individual plants and minimises evaporation and wind drift. Reticulated drip systems are preferable.

Drip irrigation is the most efficient watering system.

Reticulated systems control drip feeding for maximum efficiency.

Water-storing crystals can hold hundreds of times their weight in water. When mixed with water they form a soft gel and retain a reservoir of moisture for plant roots during dry periods. Some products can be sprayed onto plant surfaces to reduce sunburn and water loss.

Soil wetting agents allow water to penetrate deeply into soil.

Humectants, or moistening agents, attract moisture from air spaces in the soil and are particularly effective in sandy soils.

Beyond the garden

Water used outdoors for activities other than gardening can also be saved.

Wash your car or boat at a car wash that recycles water and detergents. At home, washing the car (or dog) on the lawn prevents water and detergent flowing down the drain. Choose a different place on the lawn each time.

Wash the car with a spray gun that has a trigger control.

Lawns have a limited ability to take up the nutrients from detergents. If the lawn becomes water-logged or deteriorates, your car may be compacting the soil or nutrient levels are too high. Aerate the lawn and switch to the car wash for a few months.

Swimming pool covers significantly reduce evaporative losses and can save 11,000–30,000L of water a year. An overfilled swimming pool can lose more water through splashing.

Use a broom instead of a hose to clean paths and the outside of buildings.

Save up to 30,000L of water a year by covering your swimming pool.

Waterless toilets

Toilets that don't use water for flushing can have even lower environmental impacts than water-efficient toilets and wastewater recycling systems. Waterless toilets or ‘dry sanitation’ systems do not use water to treat or transport human excreta. If appropriately designed, they conserve precious water resources and keep effluent and pollutants out of waterways and the general environment. They can also save money on your water bill.

Waterless toilets are a genuine, minimum energy, on-site alternative to centralised reticulated systems that transport the problem downstream. They can also reduce the site restrictions, and pollution and nutrient problems, of systems such as septic tanks.

They are often preferable to conventional toilets in environmentally fragile or water-scarce areas. For example, in the mid-north coast region of New South Wales, councils recommend householders install waterless toilets rather than conventional septic tank systems.

The most common type of waterless toilet, the ‘composting toilet’ (CT), has come a long way from the original pit latrine. The CT doesn’t smell if used and maintained correctly and can, in fact, be an elegant addition to a modern bathroom.

The composting toilet has come a long way from the pit latrine.

All CTs require a volume of space under the toilet floor which may necessitate the construction of either a pit or an elevated platform. They generally work best when kept warm so are ideally located on the sunny side of a house.

Waterless toilets can produce fertiliser if sufficient time is allowed and correct treatment conditions have been maintained. However, seek advice on its end use.

The CT often does more than the process that occurs in your garden compost heap. Decomposition in the holding tank or container of a CT takes place through a complex biochemical interaction of factors such as temperature, pH, desiccation and digestion by invertebrates, all taking place over an extended time period.

Waterless toilets conserve water and keep pollutants out of the environment.

Types of composting toilets

The many designs of CTs can be divided into three main types with characteristic advantages and disadvantages. Designs include commercial off-the-shelf units and owner-built systems that can be constructed using readily available materials.

Continuous composting toilets

These single container toilets receive excrement which decomposes as it moves slowly through the container and is removed as compost from the end-product chamber. Well-known designs with prefabricated models available for installation have health department approval in most parts of Australia. They may also be constructed by owner–builders.

Single containers are fitted under a bathroom and can easily replicate a flush toilet with little physical or social adjustment.

The container is permanently fitted under the toilet seat, and never has to be fully emptied as the compost can be gradually removed when it reaches the end-product chamber.

A disadvantage of the continuous system is that it may allow fresh material and pathogens (disease causing organisms) deposited on the top of the pile to contaminate the successfully decomposed end-product at the bottom of the pile.

Another drawback is that, if a problem occurs with the toilet, the system can be out of order until the problem is fixed because there is only one container. Sometimes the pile does not actually move down the slope of the container and can become compacted and very difficult to remove.

Continuous composting toilet.

Plans for continuous composting toilet.

Batch composting toilets

Batch CTs consist of two or more containers that are alternated so that the active container is being used while the pile in the fallow container has time to compost without the addition of fresh excrement and the potential for recontamination.

An example of an owner-built batch CT is the ‘wheelie-batch’. Containers are alternated underneath the toilet seat, and a perforated false floor is used to separate and drain off the liquid.

The owner-built wheelie-batch CT alternates containers underneath the toilet seat.

The fixed chamber batch is another example. Two containers are permanently in place and the seat is moved when the time comes to change containers.

The full containers in the batch system need to be replaced by an empty container. They must be disconnected from under a toilet seat or the seat moved over a new container. Batch systems can therefore take up more space in the bathroom or under the house.

Some commercially available batch CTs, including an Australian-made system, have approval for use in most parts of Australia. Some models have removable containers mounted on a turntable beneath the toilet for collecting waste, which saves space and simplifies container changeover.

The Windblad batch CT has removable containers mounted on a turntable beneath the toilet.

Self-contained composting toilets

Self-contained CTs are available for use where a composting chamber can’t be installed beneath the floor, such as an existing on-ground concrete slab. They are usually fitted with a small heater and fan to facilitate waste decomposition, and have the capacity to serve only households with a maximum of 3–4 people.

Self-contained composting toilets can be installed on an existing concrete slab.

A self-contained composting toilet fits neatly into the modern bathroom.

Maintenance of composting toilets

The CT is relatively simple technically but requires more attention than a flush toilet.

Add some carbon-based material or bulking agent, such as dry leaves or softwood shavings, frequently to the container, preferably daily or with each use. This gives the proper carbon–nitrogen mix, helps aerate the pile and prevents compacting. Some commercial suppliers say this is not necessary for their design if their directions are followed but experience indicates the addition of bulking agent helps produce good compost.

A composting toilet that is working well and correctly maintained does not smell.

A CT that is working well and correctly maintained does not smell. Offensive odours usually indicate that something is wrong and trouble-shooting directions need to be followed. Often adding bulking agent in greater quantities or more frequently removes the smell.

The pile in a CT needs to be well drained. Diverting urine away from the compost can aid the composting process by reducing moisture levels and potential odours. Liquid runoff is often treated in a sealed evapotranspiration trench or a solar evaporating tray. If the liquids have been in contact with faeces, they must be evaporated, sterilised or otherwise treated before they can be recycled as fertiliser.

Council or health department regulations require appropriate drainage and disposal for residual moisture.

Vent pipes aerate the pile and can work passively using convection. Fans are not essential but are often included in off-the-shelf systems to aid ventilation and minimise odours. Check fans occasionally to ensure they are not choked with dust or insects.

The end-product or compost needs to be removed from the container when it is sufficiently decomposed. The frequency of removal depends on the size of container, how often the system is used and local climatic conditions. The minimum ‘fallow’ period should be six months. Depending on the design and usage, the container needs to be emptied every six months to three years.

Use the compost as fertiliser dug into your garden or dispose of it according to local council regulations.

CTs do not deal with greywater from showers, kitchen and laundry so a separate greywater collection and treatment system is needed (see Wastewater reuse).

Some safety precautions

It is safest to assume that the composted end-product contains residual disease-causing pathogens. The degree of decomposition and pathogen destruction is sensitive to a range of ambient conditions in the composting mass (such as temperature, moisture and pH levels) that are difficult for the toilet owner to monitor and control.

Always use protective clothing such as gloves and mask when handling the composted end-product.

Bury the compost under at least 10cm of soil.

Do not use the compost for cultivating vegetables.

Choosing a composting toilet

For an off-the-shelf unit contact several suppliers. Tell them about the building, where the toilet will be located, how many people will be using the toilet and whether it will be on a continuous basis or only occasionally, such as in a holiday house. Ask them to recommend a suitable system for your needs and provide a quote. The cost can vary significantly depending on the design and features. Some suppliers also assist with greywater treatment systems.

Check if the supplier gives after-sales support. Ask if they have any customers with whom you could meet and discuss their experience with the CT. The cycle of usage and production of compost or end-product can take a couple of years. It is important to know that all stages of the process work satisfactorily.

Check with your local council and/or the supplier to confirm that CT design has approval in your area. Council attitudes and regulations vary, but common off-the-shelf units have state health department approval. Owner-built designs are usually cheaper to install and have been used widely for many years but often have not gone through the required approval process.

Avoid complicated designs. Simple passive systems with minimum moving parts are usually easier and cheaper to build, monitor and maintain. Designs that have more moving parts may require less maintenance if the system is working well. But if there is a problem, the more complicated designs can be more difficult to fix.

There are many types and applications of CTs. The published literature and manufacturers’ websites have more information and contacts for commercial units and owner-built designs.