How to reuse greywater around your home
If there’s one thing every Aussie knows, it’s the value of water.
On average, we all use around 125 litres of water each day, showering, washing clothes and dishes, cooking and drinking, and using the toilet and bathroom sinks. That’s a lot of water!
Almost 60% of water waste in the home is produced by personal washing from showers, baths and taps, clothes washing and dishwashers – this water is often referred to as ‘greywater’ and can actually be reused in other areas of the home.
What is greywater and how can I make the most of it?
Every household produces two kinds of wastewater – blackwater and greywater. Blackwater is wastewater that has been mixed with waste from the toilet (and also sometimes kitchen sinks and dishwashers depending on which state you live in), while greywater is water from washing machines, bathroom sinks and showers.
Blackwater is prone to contamination by disease causing pathogens, and so greywater is the main source of water that can be reused without extensive treatment.
There are multiple advantages to reusing greywater around your home:
- Reducing water bills
- Using less water resources
- Decreasing the amount of pollution and chemicals entering local waterways
- Easing the strain on wastewater treatment facilities
To increase the quality of your greywater and lessen your impact on the environment, use natural cleaning products where possible for clothes and dishwashing.
A royal flush
Did you also know that 30% of your total water use in the home is attributed to flushing the toilet? Now that’s a lot of perfectly good, clean water being used to dispose of waste.
Treated greywater is perfect for use in the toilet, and can save around 50 litres of potable water in the average household every day. Each state has different regulations regarding the treatment of greywater, so it’s best to check with your local council first before installing any new system.
Greywater treatment and disinfection systems designed specifically to produce water for indoor use generally consist of the following mechanisms:
- Coarse filtration to remove large particles
- Fine filtration and biological treatment to break down organic matter
- Disinfection by chemical or electrical means (chlorine, UV, ozone)
They can be bought and installed by a plumbing professional, or you can create a system yourself – but of course, in both cases, make sure the completed system complies with local government regulations.
In some cases, water from the bathroom sink and shower can be diverted directly to the toilet after being coarsely filtered (provided it is used immediately and not stored for more than 24 hours before it is reused or sent to the sewage system).
A simple diverter valve may be all you need in some cases where the water does not need to be extensively treated. Other options include a closed-loop system or a surge tank.
Another way to reuse greywater (and reduce overall water use in your home) is to redirect it with some clever pipework towards your garden. This type of reuse does not require the greywater to be treated, however it is safer to use untreated water for sub-surface irrigation systems such as slotted drainage pipe and special driplines.
One thing to note before using your greywater is to take a look at the kind of detergents in your laundry and kitchen to see what ingredients they contain. Some common chemicals, such as phosphorus and sodium, can be damaging to your plants and lawn so opt instead for ‘biocompatible’ or ‘biodegradable’ solutions if you wish to reuse greywater on your garden.
Don’t use greywater on edible plants like fruit trees, herb plantings or vegetable gardens! The chemical load can transfer into what the plant produces.