Australia is the driest inhabited country on Earth, with the least amount of water in our rivers, the lowest run-off and the smallest areas of permanent wetlands globally. So it makes sense to be reusing our water through greywater infrastructure in our homes.
But with so many different options available, how do you know which system is best for you? If you’re ready to take the plunge, prepare yourself with this handy guide below. Your garden will be thanking you in no time.
What is greywater?
Greywater, in simple terms, is water that has been used elsewhere in the household, not including water from the toilet (referred to as blackwater). Most people don’t use kitchen greywater because it is generally too contaminated with sodium, food scraps and grease to be usable in the garden.
The simplest way to collect greywater is to do it manually, placing buckets under the shower that can then be used to water the garden. But that is quite labour intensive and many people who rely on greywater will opt to install infrastructure to their pipes (called direct diversion) to redirect the water for their needs.
When using greywater, it’s vital to think carefully about the products you use in the shower or laundry. There are products that are specifically labelled as suitable for greywater usage – seek them out and don’t use chemical-based cleaning or washing products such as salt, phosphates or enzymes, and avoid diverting things like hair dyes or bleach into your garden.
Diversion options
Installing direct diversion pipes may be a job for a plumber, depending on your home and confidence, especially in modern homes where the pipes are built into the walls or floor. The diversion pipe will also need to be buried in a shallow trench ensuring the greywater is evenly dispersed through the garden rather than pooling on the surface at the water outlet.
If you wish to disperse the greywater across a larger area or in a more targeted way, you may need a greywater sump, filter and water pump. These can store water, filter out any solids from the greywater and direct it around your property. Many of these units include an overflow that will automatically direct excess or dirty water to the sewer.
There’s a lot of variety (and price) for this equipment depending on the size of your property and whether you wish to direct water to a single garden bed or install a larger, “whole-of-house” system. Either way, it’s essential to follow local council guidelines, which vary from region to region.
Using greywater in urban environments
For Alan Leenaerts, who lives in Greensborough in Melbourne’s north-eastern suburbs, it made sense to set up a greywater system from his bathroom for his lawn. His home has been entirely off the water grid since 2001, so he uses greywater to make his home’s rainwater tanks last longer.
Along with a 30,000-litre rainwater storage capacity in 10 tanks, he has greywater collection points from the washing machine and shower. Leenaerts says he installed his greywater pipes himself for $70 from Bunnings and has only needed to replace them once in 23 years. As they empty directly on to his lawns, he didn’t require a council permit.
“The main benefit of going off-grid in the suburbs is that I don’t steal water from the nearby Thompson or Yarra rivers … It’s the easiest way to reduce household impact on the planet and reduce climate change.”
Is greywater going to work in your garden?
Almost all gardens will be suited to greywater, including those growing fruit trees, shrubs and native Australian trees. The exception to this is vegetable gardens – because of the potential for the pathogens in greywater to be in direct contact with edible parts of the vegetables, avoid using greywater on your veggie gardens.
Using greywater doesn’t preclude the need to keep composting and using mulch in your garden beds – in fact it’s a good idea to use liquid trace elements to lower the pH levels in your soil. Greywater can contain metals and salts that accumulate in soil, which can lead to soil salinity and sodicity.
Sybil Sharvelle, a civil and environmental engineering professor at Colorado State University, says greywater should only be applied in tandem with climate-appropriate landscaping, meaning you shouldn’t expect to grow a water-intensive garden from greywater in dry conditions.
With Australia’s summers getting hotter and water becoming scarcer, there’s no doubt greywater is a vital climate resource – but it’s worth putting in the effort to do it right, to reap the long-term water-saving benefits.