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Do Grey Water Systems Make Sense in Australia?

Adjusting your lifestyle to be more sustainable can be difficult, but there are certain things you can do to help. For example, using a home grey water system is a great way to save and recycle water while reducing energy usage.  

Grey water systems are simple to install and can be used for various purposes. Reusing grey water reduces the amount of freshwater you need for your household, and the amount of waste that enters a septic system or a sewer. 

Installing a grey water system is the perfect way to live more sustainably and become more eco-friendly.

What are Home Grey Water Systems? 

A home grey water system diverts wastewater into either a treatment and recycling system or irrigation. These systems filter water from washing machines or bathtubs to be recycled and used again, instead of flowing straight to a septic system.

What is Grey Water Used For? 

Grey water can be used for many things since it is recycled water. Many choose to use their grey water for irrigation. It is important to use only plant-friendly products that do not contain chlorine bleach or salt. 

You can also reuse grey water in your toilets, but it is generally not recommended, because it can become smelly quickly if it sits around too long. 

A better way to use grey water for a toilet is to pour a bucket of the grey water into your toilet every time you flush. This way, it doesn’t sit around in the tank and become grimey. 

Grey water can also be used for landscape maintenance and laundry. Never use grey water in the kitchen, as it could be contaminated with bacteria or other chemicals.

Can you drink grey water?

Grey water is unsafe to ingest and is not potable. Grey water can potentially carry many harmful viruses and bacteria that can make you sick, which is why it is unsafe to drink. 


How Does a Grey Water System Work? 

Grey water comes from basins, showers, and baths piped to a surge tank using a grey water hose. It is held for a short time before being discharged to a treatment system or irrigation. You can divert the grey water by using gravity or a greywater pump. Any container that holds an initial surge of water is used as the surge tank. 

It must be used just to hold the water and not store it long term, like you would with a water tank. The surge tank must be emptied when grey water is distributed to the treatment or irrigation system. Grey water cannot sit for extended amounts of time in the grey water tank. 

Gravity System

A gravity grey water system should be used when there is adequate “fall” (or high to low height difference) from the bathroom or laundry drain for the tank to surge. Your surge tank must have a trapped overflow and must be:

  • Sealed
  • Vented
  • Be vermin proof
  • Discharged straight into the sewer or to an on-the-spot discharge 

Pumped System

With a manually pumped grey water system, you use a float switch and a submersible pump. A pumped system must be used if there is inadequate fall. In some cases, your surge tank can be completely or partially below ground level. 

Grey water from indoor sources drains to a pump basin, which gets sent out to the landscape. There are no storage tanks or filters, so a pumped system is minimal maintenance.

Benefits of Grey Water Systems 

The primary benefit is that you save lots of water and some money. However, using home grey water systems offer more benefits, such as increasing the productivity of a sustainable backyard ecosystem that can provide shelter and food for wildlife.

Overall, using a grey water system:

  • Reduces water waste
  • Reduces energy by warming new water 
  • Builds the value of your home
  • It helps support plant growth
  • Reduces pollution in local bodies of water

What if My Home Produces More Grey Water Than Needed for Irrigation?

In many climates, especially Australian climates, it is difficult to produce an overabundance of grey water. You might be surprised by how much water your soil can absorb.

In wet and humid regions, some Australians might use constructed wetlands to help soak in some of the excess water. However, it is unlikely that you will have extra water. Australian homes can produce about 400 litres of grey water daily, which equals about 40 percent of water use. 

Frequently Asked Questions 

These are some frequently asked questions regarding home grey water systems.

What is grey water?

Grey water is relatively lean wastewater from sinks, baths, kitchen appliances, or washing machines. Essentially, grey water is wastewater generated in your home without fecal contamination.

What is a grey water pump?

A grey water pump fits within a grey water recycling system that pumps your wastewater from multiple sources. The grey water pump takes water from the washing machine, bathtub, dishwasher, and more and recycles it to be used again.

Is grey water safe? 

Grey water is safe in most cases, but it should never be used to drink. It can carry bacteria and viruses. Grey water is safe to flush toilets for irrigation, laundry, and landscaping. 

Are there any drawbacks to using a grey water system?

While using a grey water system is primarily beneficial, there are potential drawbacks associated with grey water. Grey water can never be used for drinking water, as it can potentially contain harmful viruses and bacteria. 

If you do not use your grey water system properly, or if it sits for too long, the grey water can create problems from the particulates in the water. It can also cause damage to foliage, especially if there are chemicals in the grey water.

How long can grey water be stored?

Grey water should be stored for up to 24 hours. If you store your grey water for too long, it will begin to break down and can start to smell bad. 

What is grey water vs black water?

Grey water is the wastewater that drains from your shower, bathtub, and dishwasher (if using environmentally safe dish soap) and is filtered and reused. It can be reused for your garden, lawn, or washing machine. 

While grey water contains some bacteria, it is generally not harmful if used for these purposes. Black water contains human waste and is unsafe to use again. Black water must be stored in its own tank and should be disposed of carefully.

Final Thoughts 

Home grey water systems are simple to install, easy to use, and are beneficial to the environment. Recycling water is excellent for keeping up with your irrigation system or keeping up your household needs. 

Not only will you save money, but you will drastically reduce your water usage, which will help you become more environmentally friendly.