Greywater Case Study – small cottage lot on the Swan Coastal Plain

This case study details the incorporation of
 a greywater system into the design of a new home. The owners of a 350sqm block in Perth’s northern suburbs were offered an incentive by the land developer for installing a greywater system and other environmental initiatives into the design of their new home.

Given the small size of the block and footprint of the house there was limited space remaining for garden areas, with only a small area at the front plus an internal courtyard being available. The solution was a laundry-only greywater system that would reuse the water from the washing machine.

System make and model

The G-Flow is a low-cost above-ground unit suitable for this application. An extension to the washing machine’s own drain hose is threaded through an underground sleeve and pumps the water into the unit. Alternatively, a gravity feed of wastewater could be fed through a conventional pipe under slab if the GDD was buried inside a service pit. In existing homes the washing machine drain hose is passed through the external wall by drilling a hole in a suitable location.

An overflow pipe is connected to the main sewer line, and a diversion valve allows water to be sent direct to sewer without going through the unit (e.g. in case of a power failure).

The G-Flow Greywater System is a low-cost above-ground unit suitable for a small cottage lot.


Irrigation area

The total irrigated garden area was 10m² made up of planters in the courtyard plus two small garden beds. An additional strip intended for greywater was assessed by the greywater professional and deemed to be too narrow to comply with the 300mm setback requirement in the Code.

Greywater calculations prepared for submission to Council showed the minimum Application Area as 20sqm (4 bedroom house, hence assumed occupants = 5; laundry only 5 x 40L/day = 200L/ day; Soil Category 1 = Sands on the Swan Coastal Plain, with a Design Irrigation Rate of 10mm/day; Minimum area required = 200/10 = 20m²). As the available area was only half of this, the system is run on a plug-in timer for only 12 hours a day.


Outcome/Water savings

A cost effective irrigation system that can regularly water all the garden beds and keep them green through summer.

WaterCraft WA

I love using Grey water in my garden because it allows me to minimise the use of scheme water in our garden watering regime with only small changes to the type of cleaning products we use in our laundry and bathroom. It also allows me peace of mind every time I take a shower knowing the water isn’t just going down the drain but directly into my beloved garden. 

Andrew Beck
Sustainable Garden Design Perth

Having Greywater go to my garden means my plants get watered every day of the year when I’m home. The water savings in summer are huge. Installing a greywater system at my own new build was a must, along with a Rainwater tank. Putting these systems in during the build process is easy compared to retrofitting, and generally cheaper. ‘Water Capture’ sell, install and service Greywater systems in Perth. 

Mark Harland
Water Capture

WaterCraft service a lot of greywater systems across the metro area and see many gardens thriving on the use of greywater. Frequent watering with traces of soap and nutrients works really well for plants on poor sandy soils. But just as you wouldn’t expect your mains water retic system to run for years without any attention, don’t expect your greywater system to keep running without a service!

Gareth Almond

About The Author

Gareth Almond

Gareth Almond has designed and installed water-saving systems in the Perth area for over 10 years. His business specialises in meticulous installations of all sizes of rainwater tank from the very small on a patio up to very large for rural properties. He particularly enjoys the more challenging work. Gareth also installs and services the AWWS range of greywater systems across the metro area for garden irrigation using household wastewater. He has developed his own suite of modelling software to help determine the most efficient water saving options and designs systems to maximise cost-benefit, which would typically include the pumped supply of rainwater back into the home. Gareth has an Honours degree in Surveying Science and spent the first part of his career doing fieldwork around the world and then as a researcher and technical manager before returning to site work in the water recycling business. He is also heavily involved in volunteer work for various organisations.