Please click on a question topic.
Please click on a question topic.
- What is greywater and why should I consider reusing it?
- What are the benefits of greywater reuse?
- How do I safely reuse greywater?
- What types of greywater reuse systems are available?
- What kind of maintenance do greywater reuse systems require?
- What are the environmental effects of greywater reuse?
Greywater is wastewater from sources other than the toilet. This includes wastewater from the laundry, bathroom and kitchen. Kitchen greywater is usually excluded from the greywater stream as it contains contaminants such as fats, oils and grease. Greywater can provide an excellent alternative resource for garden irrigation as it is independent of climate and is a consistent supply year round, even through periods of drought. Each system needs to be carefully planned and designed to ensure the most effective reuse of greywater, which will ensure the greatest potable water savings are achieved. Greywater can be safely reused through appropriate selection of bathroom and laundry products and a diligent approach to greywater system maintenance.
Why Recycle Greywater?
The average Australian household uses about 800 L per day for both inside and outside use. That’s 300 kL of water per year, and nearly 40% of that use is on gardens. Typical values for the volume of greywater is about 100 litres per person per day, so reusing greywater from your bathroom and laundry into the garden could give you an extra 100 kilolitres (100,000 L) of irrigation water a year for a family of three.
Reusing laundry and bathroom wastewater on your garden is just another way of moving towards a more sustainable lifestyle. What’s more, it’s a practical step that is just as easily applied in the suburbs as it is in the country.
Water is too valuable a resource to waste, and any endeavour to reduce potable water demand or reduce wastewater disposal and treatment (and the energy this consumes) should be encouraged. More importantly, we should endeavour to reduce our water consumption by instigating a range of strategies which include installing reduced-flow shower heads, using water-efficient washing machines, turning off the tap when cleaning your teeth, and taking shorter showers.
What Greywater System to Choose
A large number of greywater systems have now been approved in WA. You can download a copy of all the approved greywater systems from the Department of Health website (www.public.health.wa.gov.au), or ask your Local Council for a copy. For Diversion Systems, it is now possible to have either subsurface piped trenches or subsurface dripper irrigation, gravity-fed systems or pumped systems, and filter systems or tank systems. Greywater Treatment Systems produce a higher standard of effluent which, in some circumstances, can be used for toilet flushing and as a source for the laundry.
Greywater Recycling Strategies
Greywater from sources such as the laundry and bathroom are allowed to be reused in a number of different ways. These include subsurface drain systems and subsurface dripper irrigation for plant irrigation. This includes sewered blocks, provided the appropriate application (and fees paid) is submitted and approved by the Health Department, via the local government council. Sometimes the Water Corporation must also approve the installation of a greywater system in some areas. A licensed plumber is required for any changes to the sewer system.
Greywater cannot be used to irrigate a vegetable garden that contains below-ground food crops such as onions, potatoes and carrots, but can be used on above-ground crops such as tomatoes, broccoli and corn, and on fruit trees, lawn areas and on other plants (both exotic and native shrubs and trees). It is also possible to manually bucket greywater from the laundry trough to water plants. Placing greywater in the root zone of plants is the most effective way to ensure maximum uptake of both the water and the range of nutrients which are available in greywater.
A word of caution: many native plants (e.g. the family Proteaceae such as grevillea, banksia and hakea) are susceptible to high levels of phosphate. Some introduced (exotic) plants, such as azaleas, camellias and gardenias, do not like the alkaline nature of some greywater sources. It is best not to use greywater on any of these types of plants.
Through careful planning and appropriate system design, greywater reuse can provide many benefits, to the householder, garden, and the environment.
Benefits for Householders
-Reduced water bills of up to 30% can be achieved, through careful system design, which considers the most appropriate end use, whether that be irrigation or in-house reuse.
-Greywater reuse is another way to move towards a sustainable lifestyle. It increases our awareness of how the water cycle works as the factors affecting onsite wastewater disposal become familiar to the householder.
-Greywater as a resource is independent of climate and so is not affected by reductions in rainfall. It is consistent year round.
-Reduced waste water flows to the local waste water treatment plant will result in lower energy requirements, reduced pumping costs, and reduced loading on sewer infrastructure prolonging its life and delaying the requirement for significant capital renovations or expansion. The benefits of this will be seen by the householder should widespread uptake of greywater technology occur.
-Greywater which has undergone a high level of treatment can be re-used in-house, for toilet flushing and washing machines, where the demand is year round.
Benefits to the Garden
-Healthy, vibrant gardens can be maintained even during periods of drought.
-Gardens can be irrigated with greywater that has undergone only a minimal level of treatment, removal of suspended solids, through subsurface irrigation.
-Irrigation of gardens can occur during periods where water restrictions are in place.
-Greywater contains nutrients, such as nitrogen and phosphorus, that can be beneficial to plant growth, which would otherwise be wasted.
-Greywater reuse allows potable water supplies to be used only where necessary, such as irrigation of vegetable types and plants which for which greywater irrigation is inappropriate.
Benefits to the Environment
-Extraction of ground water supplies is at a sustainable rate.
-Reduced reliance on potable water supplies and provides greater security for future water supplies.
The responsible collection and use of greywater in the home or gardens has many benefits. While there are risks to reusing greywater, a few simple steps and suggestions should be followed.
Greywater can be reused safely by adopting the following:
-Select a greywater system that has been approved for installation in WA.
-Use a licensed plumber to install the system
-Use environment-friendly soaps and detergents. Select washing powders or liquids which contain low levels of phosphorus, boron and sodium. Generally, liquid laundry detergents have lower salt content than powders.
-Undertake regular maintenance, such as cleaning the filters or tanks, checking pumps, flushing irrigation lines, cleaning vacuum breakers. Read the homeowner’s guide for this system, and follow the maintenance schedule.
-Divert greywater from your system back into the sewer line during winter when your garden may not need additional watering.
-Monitor plant and soil response to greywater irrigation. Some plants do not survive in alkaline or salty soil conditions.
-Only use purple drip-line in subsurface irrigation (100 mm below the surface of soil or mulch).
-Wear gloves when you are performing maintenance. Wash your hands thoroughly afterwards.
-Greywater can be used to irrigate above-ground food crops. There should not be contact of any edible fruit or vegetable part with the soil.
Please be mindful of the following:
-Do not divert any greywater from the kitchen as this does not have approval from the Department of Health.
-Greywater must not be sprayed onto edible (food) plants.
-Do not overuse bleaches, fabric softeners or washing products containing borax or chlorine. Biodegradable products should be used.
-Do not use greywater from the washing of nappies and/or soiled clothing. This includes materials used in painting, hair dyes or other chemicals.
-Do not use greywater from any source if a member of the family has an infectious disease, such as diarrhoea, intestinal parasites or hepatitis.
-Greywater must not be stored for any length of time – other than that required if a sedimentation tank is used in the system. Stored greywater will turn septic and cause unpleasant smells.
-Do not use greywater to top up rainwater tanks or swimming pools, nor wash vehicles or paths.
There are three different types of Greywater systems approved for use in WA, and each has a different end use or conditions of approval. Most greywater systems are Greywater Diversion Devices (GDD). The second type of greywater system is a Greywater Treatment System (GTS). The third category of approval is manual bucketing. This means that you can collect the wash water from the laundry trough, for example, and use this to water plants.
GDD provide only a minimal level of treatment, which is the filtering or removal of solids, such as hair and lint. The recycled greywater can only be used for subsurface garden irrigation, which includes dripline or piped trenches. These are installed below ground with 100 mm of soil or mulch over the irrigation system. Subsurface irrigation reduces the risk to humans, pets and other animals of coming into contact with disease-causing organisms.
There are two main types of Diversion Devices:
1. Gravity device
Greywater is diverted from the source, usually by a hand-activated tap or valve, and flows by the use of gravity to the irrigation field. These systems are ideal if the property has sufficient slope. For dripline at least two metes of vertical head pressure is required for the drippers to emit water. For piped trench systems a minimal fall is all that is required to disperse greywater into the soil.
2. Pump device
Pump devices often incorporate a surge tank to cope with sudden influxes of greywater, and then it is pumped under pressure to the irrigation field. The surge tank acts as a temporary holding tank and not as a storage tank, as greywater cannot be stored for more than twenty-four hours as it can turn ‘septic’. Some pump systems are activated as soon as greywater enters the tank, while others collect greywater during the day (or night) and pump out when a reasonable volume is obtained.
GTSs use a number of strategies to filter, clean and disinfect greywater so that it can be safely used in the house. Treatment will reduce solids, nutrients and micro-organisms. This allows the treated greywater to be returned in-house and used for toilet flushing and/or for laundry use. The effluent from GTS approved in WA, can also be used for garden irrigation.
Some Greywater Treatment systems have a service agreement as part of the approval and installation conditions. This means that the homeowner pays an annual fee for regular checking and monitoring of the system. It is important that treated greywater is safe, is kept at a high quality and contains no disease-causing organisms. Only authorised, trained service contractors can undertake this service work.
What are Some Typical Costs for Installation?
Simple gravity systems may only cost hundreds of dollars for the unit, with installation extra depending on plumber and installer time, what piping needs changing, what application fees are required, and so on.
Pumped diversion devices could be up to several thousand dollars for the unit, with installation several thousand dollars more. Treatment systems are more expensive and may be ten thousand dollars or more fully installed.
How Can I find Out More?
You can obtain list of the approved greywater systems by contacting your local Council or downloading from the Health Department website. A quick internet search for ‘approved greywater systems in WA’ will enable you to find the list, and save and print it off in a pdf format.
Greywater Diversion Devices (GDD) require some maintenance, which is often undertaken by the homeowner. Greywater Treatment Systems (GTS) also require maintenance but this has to be performed by a qualified person under the agreement of installation with the manufacturer or installer.
This fact sheet only discusses Diversion Devices, which are the most common greywater systems installed in WA.
The amount of maintenance will depend on the volume of daily greywater. As more and more greywater passes into the system hair and lint is trapped and this slowly accumulates. Regular cleaning and servicing of any greywater system is essential to maintain optimum operation and extend the life of the system.
Filters need regular cleaning, often every few days to two weeks. The Operations Manual for your system will give instructions about how this is undertaken. When filters become blocked then the greywater is usually diverted to the sewer or septic system and is not available for irrigation.
The filter system varies from stainless steel strainers to cloth or nylon bags to sponge material. In some cases filters need complete replacement on a regular basis.
Sediment Tank Systems
Tank systems tend to require less maintenance, but solids will build up in the tank. Under the Code of Practice tank systems need a pump out every five years.
Some greywater systems may have two tanks or one filter and a pump tank, or some other short storage capability. While the sedimentation tank requires a five-yearly cleanout, the pump tank should be serviced very year.
While pumps can last many years, a small amount of servicing should be undertaken every three to six months. Hair and lint can block the pump intake, causing eventual pump failure.
Irrigation piping and drippers can become blocked with soap scum and small suspended solid particles. Systems should have vacuum breakers and flush valves, as a minimum, as standard irrigation best practice.
Greywater reuse for irrigation has the potential to save significant amounts of mains water as well as providing fertilisers for your plants.
However, greywater can contain salts, disease organisms, traces of fats and oils (even human body fats), soaps and detergents (which can make the greywater alkaline), and an array of nutrients, some of which could be harmful.
If you intend to reuse greywater for garden irrigation then you should carefully choose the types of household cleaners, detergents, soaps and other chemical products you use.
Effects on Plants
Too much greywater application continuously to one area may cause waterlogging of roots, inhibiting plant growth and even causing plant death. You may find your plants looking unhealthy, or there is evidence of pests and disease on the plants or even obvious discolorisation of foliage.
Some laundry products contain levels of phosphorus which would be detrimental to some native plants, such as Banksias, Grevilleas and Hakeas of the Family Proteaceae. Not all natives are phosphorus-sensitive, but you should try to minimise the phosphorus content of the detergents you use by choosing those that are low in phosphorus.
Greywater tends to be alkaline, which can alter the pH of the soil over prolonged application. Not only does this affect soil properties but it may inhibit the uptake of some nutrients by plants as well as causing toxicity by other nutrients.
Effects on Soil
If greywater is not filtered in some way to remove suspended solids and organic matter, pore spaces in soils can become blocked.
Some laundry detergents are high in salt (typically as a filler in powders) and these will tend to accumulate in the soil profile and cause soil structure collapse. Liquid detergents tend to have much lower salt content.
Excessive fats and oils in greywater sources can make some soils water-repellent, and water may pool or run-off. Generally, the detergent fraction in greywater helps to reduce the natural water-repellency of some Australian soils.
Bleaches, disinfectants and germicides should be avoided as much as possible as these chemicals will kill soil micro-organisms and seriously affect soil health. Even eucalyptus oil and tea tree oil will have the same effect. If you need to use these substances make sure you divert the water to the sewer or use them in a laundry bucket and pour the solution down the toilet.
Effects on the Environment
Excess nutrients may run-off or leach through the soil to enter waterways and aquifers, resulting in algal blooms or other water quality issues. Some types of detergents and optical brighteners are slow to bio-degrade and may persist in the environment for many months.
Want to Find Out More?
In the first instance, contact the Environmental Health Officer at your local council if you have any questions or concerns about greywater recycling at home.
If you wish to find information about the salt and phosphorus content of the household products you use visit www.lanfaxlabs.com.au. Many nurseries and hardware’s supply pH test kits and it is useful to monitor and test the soil for changes in acidity.