Gardening with greywater – Soil and plant information
If you are going to be using greywater on your garden and there are a number of things you need to consider to ensure your plants and soils, and those of your neighbours stay healthy and happy.
These pages will assist you with practical advice on using greywater for gardening and provide resources for landscapers wishing to incorporate greywater management into garden design.
Gardening
Like most things, what you get out of greywater depends on what you put in. As you know gardens are living things and the chemicals and bacteria we add to grey water can have short and long term effects on your garden and indirectly your health. Fortunately most impacts can be addressed by being careful about what you add to greywater and being careful about how you store, treat and use greywater. Because greywater is associated with health risks, it is usually applied to the garden below ground or at least under mulch. Greywater is not as good as rainwater or potable water for plants.
Our section on GreySmart Household Cleaning and Personal Care Products helps you choose detergents and other household products which are GreySmart (garden friendly). Having given you the warnings many gardeners have really enjoyed being able to recycle their home water in such a rewarding way.
The main things to consider when irrigating with greywater are:
- Greywater volume potentially available as calculated using H2OmeCalc
- Greywater is supplied all year around and even when it doesn’t rain so it can be very useful if rainfall is limited
- Greywater quality
- Source control is key, what you put down the drain is what you get in your garden
- Soil type ( Soil texture, water holding capacity and pH)
- Loamy soils that allow water to infiltrate easily and then hold on the water so it doesn’t keep draining away are ideal. Avoid moderate to high clay content soils and sandy soils. Remember, when you irrigate you don’t want to see surface runoff of greywater into places where it shouldn’t be going or excessive deep drainage! See more information on drainage and design irrigation rate (DIR) in the Drainage section.
- Site considerations (land fill, site shading, slope, setback distances, natural waterways, dwellings, paths/hard surfaces, swimming pools, land area available for greywater irrigation, erosion potential)
- Choosing the right site for greywater use is critical and many guidelines indicated setback distance to help minimize greywater moving away from the area irrigated and into area where it can be detrimental to the environment or human health.
- Climate and local rainfall
- Groundwater
- Care should be taken to ensure that groundwater used for drinking water is not contaminated by the use of greywater. Special attention needs to be given to the protection of in-ground rainwater tanks from contamination.
- Vegetation and plant types
As a guide the most technical approach to these issues we have seen is in Queensland in the Guidelines for Councils assessing the suitability of small blocks for greywater use.