A Quick Guide to Home Greywater Systems

Recycling Water

With northern NSW recently devastated by floods, it is strange to think that in a time of excess water, we’d need to think about recycling water. It is also noteworthy that many parts of the country are currently suffering droughts and could face certain water shortages, the majority of Australians still use clean drinking water for most household uses. Some of this precious resource could be conserved by recycling greywater.

Regulations about greywater use are different in many parts of Australia. For example, in Victoria, greywater can be used either treated or untreated, while for most states, certain conditions apply to each type of use.

This guide offers general suggestions on recycling water at home, but it is important to consult with a licensed plumber before you alter any of your household plumbing.

What is a Greywater System?

A greywater system takes water that has already been used from your laundry, shower and sink and repurpose it to water gardens or flush the toilet. Greywater is different from blackwater (aka sewage). While greywater may sometimes contain residuals like dirt, hair, grease, etc from its first use, they aren’t toxic like blackwater and can be reused in some applications.

The average Australian household uses many litres of water every day. Showers use the most water, followed by washing machines. Here’s a quick overview of water consumption within the areas of the home.

Reusing Greywater Outdoors

When used responsibly, greywater can be:

  • A source of irrigation water all year round
  • A relatively easy and safe source of water to access and use
  • A good source of nutrients for plants.

From Sink to Soil – Capture all the water from your sinks, showers and other drains into one place called a “surge tank” – a system that can take a lot of water at once and then slow down the flow. From there you want to allow the water to slow down just enough so any solids can settle out to the bottom and then let the cleaner water move on. The water then travels outside, into the garden and finally into drip points above mulch beds.

As aquifers run dry and water becomes scarce, treated greywater is essential to transitioning to a more sustainable system and tiny house dwellers are on the front lines of this transition. Here’s a simple DIY diversion system to irrigate a small garden.

Take a 1 1/2″ pvc pipe, attach it to the plumbing of the house and bury it in the garden. Place the pipe in a 2 foot deep ditch that had been lined with gravel and landscape fabric. Along the pipe, drill little holes to allow the water to escape. This technique is very similar to a french drain.

Reusing Greywater Indoors

From Sink to Toilet – Why waste clean, potable water to flush poo? It’s convenient to install a bathroom greywater system, but the idea comes with a hefty price tag. DIY versions of the sink-to-toilet systems are available, but for the best and most sanitary system, green architects recommend greywater treatment systems such as ,HydraLoop,Aqualoop, or ,Aquacell.


  • Integrates into your home plumbing system
  • Professional systems are warrantied
  • Approved by some local building codes


  • The most costly system
  • Requires periodic maintenance on the collection and treatment aspects of the system

Greywater Systems

1. Diversion-Only

This system can be as simple as bucketing shower or laundry water onto the garden, adding a three-way valve to your shower or laundry waste pipe, or connecting a hose to the end of your washing machine’s wastewater hose. The diversion-only method is generally adequate for limited, irregular use of greywater.

2. Diversion and Filtration

If you want to use greywater on a more permanent basis, consider a system that delivers water at a more controlled rate via ,subsurface irrigation. This is normally done with a ,surge tank, which can be part of a diversion-only or a diversion-and-filtration system. Treatment systems will usually have a storage tank that performs the same task.

3. Filtration and Disinfection

There are a variety of ways of treating greywater, including biological, chemical and a combination of both. Treated greywater can be used in a wide range of applications, including laundry washing (in some states), and can also be stored—something that should not be done with untreated greywater.

Most treatment systems are expensive, usually in excess of $5000, and often require ongoing energy, maintenance and periodic water quality testing costs. Treatment systems may be ideal for some applications, especially where large volumes of greywater are produced daily and the gardens are big enough to utilise the water. However, it may be simpler and cheaper to use a rainwater tank for laundry water supply, combined with a simple diversion-and-filter system for laundry and bathroom greywater reuse.

Grey Water For Off-Grid Living

Living off-the-grid has its own set of challenges that requires learning new ways of finding, developing and using resources. And learning the most efficient use of greywater is critical to sustaining your off grid home, cabin or tiny house.

Since you won’t be producing much water waste to begin with, first you must install a rain catchment system to collect more water then pair it with a diversion and filtration system to water your garden and flush waste.

When using greywater for your garden, make sure your soil drains well, you can do this by doing a simple perk test (a water infiltration test) on your soil. Then figure out how many gallons of greywater you will produce in a given day and design the system to handle that plus a 25% margin.

Plan your drain lines down hill from your point of use, digging ditches deeper and deeper if you need to get a steep slope for proper drainage. Having the water move away from your house is critical, so make plans to drain at least 30 feet away to avoid moisture issues.

Greywater Regulations

Some states have a code of practice in wastewater management systems for home use, while others don’t. Generally, local councils sign off on any installation and operation of onsite greywater management systems, carry out inspections, and work with property owners to repair faults. Click below for more guidance on installing greywater systems for domestic use in your home state.

Greywater DOs and DON’Ts

Here are some basic, common sense rules to minimise the risks associated with greywater reuse –

  • DO Wash your hands with clean, potable water after watering with greywater
  • DO Divert greywater to the sewer during wet periods
  • DO Use biodegradable soaps, shampoos, dish soap and detergent so as not to damage the soil, plants or watershed.
  • DO Use garden-friendly cleaning products that are low in sodium and phosphorus
  • DO Keep children away from areas where greywater is used until it has soaked into the ground.
  • DON’T Use greywater that contains disinfectants and bleaches
  • DON’T Store untreated greywater for more than 24 hours
  • DON’T Use greywater on vegetables and herbs that are to be eaten raw
  • DON’T Use greywater sourced from washing nappies or soiled clothes
  • DON’T Use greywater from the kitchen, unless it has been treated
  • DON’T Let greywater leave your property
  • DON’T Use greywater that is still hot as it will kill beneficial organisms in the soil
  • DON’T Let greywater form into puddles or flow onto other properties, watercourses and drains.
  • DON’T Keep watering in one spot – salts and other contaminants will build up
  • DON’T Rotate greywater use with mains and rainwater – this will help flush salts from the soil
Final Tip:

Living your best life off-the-grid is easier and more sustainable than ever! Consult our professional team to assess your property and make suggestions on water conservation systems that will work best for your modular home.

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