Greywater is the wastewater stream from all sources other than the toilet (toilet water is often called blackwater or sewage).

Kitchen greywater, however, (and dishwasher water) is not to be reused as this can contain oil, fats and food scraps, which do not break down easily and can easily clog irrigation filters and pipes. This means that householders can easily reuse greywater from the bathroom/s (shower, handbasins and bath) and the laundry.

The average Australian household uses about 800 L per day for both inside and outside use. That’s 300 kL of water per year, and 40% of that use is on gardens. Typical values for the volume of greywater produced is 100 litres per person per day, so reusing greywater into the garden could give you an extra 100 kilolitres (100,000 L) of free water a year.

Reusing laundry and bathroom wastewater on your garden is just another way of moving towards a more sustainable lifestyle.

What’s more, it’s a practical step that is just as easily applied in the suburbs as it is in the country.

Rainwater Collection and Use

Rainwater collection and use is becoming very common in new homes. The average home could easily harvest 100,000 L each year from their roof, and this water can be used to offset the water budget for your home.

Installing a rainwater tank, no matter what size, is a small step that you could take to become self-reliant. Generally, the larger the tank the more water you can collect and use. If you wanted to use rainwater to flush toilets and provide water to the laundry, then you would probably need at least a 9,000 L tank. It is not uncommon to install 30,000 to 50,000 L tanks for this purpose.

Generally, the most popular tanks for urban backyards are either made from steel or from polyethylene. Large tanks (50,000 L plus) are typically steel-liner tanks. These have a steel outer structure with a flexible poly liner inside.

Most people want to use the harvested rainwater - either for drinking or to flush toilets or to wash clothes. Rainwater is most often pumped to the house, although gravity can be used in some cases to direct rainwater to fixtures in the house. Either a submersible pump, a pressure-tank pump or a pressure-switch pump is used to supply rainwater when required. When the tap is turned on, or the toilet flushes, the pump is activated and gently pumps water to fill the cistern, or enter the kitchen sink or washing machine. 
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