shutterstock_156930869It has been estimated that every household could save up to 50,000 litres of drinking water a year simply by re-using their grey water. This article looks at the benefits of grey water and how it can be recycled in the home.

What is grey water?

Grey water is the waste water that is produced from showers, baths, basins and washing machines. While not suitable for drinking, grey water can be re-used to water gardens, saving thousands of litres of valuable drinking water.

Grey water usually has soaps and detergents in it, which contain salts, phosphorous and nitrogen, all of which plants need to thrive. Gardens watered with grey water through drip irrigation usually need less fertiliser as a result.

How can it be re-used?

There are three main ways that grey water can be re-used.

  1. By bucket – This is the easiest way to re-use grey water and involves manually bucketing water from the bath or washing machine directly onto your garden.
  2. By diversion – A grey water diversion device is a device installed by a plumber that diverts water from showers, baths, sinks and washing machines into a small holding tank, which is connected to an irrigation system.
  3. By treatment – A grey water treatment system installed by a plumber reduces solids, pollutants and micro-organisms in grey water so that it can be re-used to wash clothes, flush toilets and water gardens. It is colourless and odourless after treatment, which involves coarse and fine filtration and ultraviolet treatment.

Safety precautions

While grey water is perfectly safe if handled properly, it can pose a potential health risk if the following precautions are not taken:

  • Do not drink grey water
  • Do not let children or pets handle grey water
  • Always wash your hands after handling grey water
  • Do not store grey water for more than a day, unless it has been treated
  • Do not re-use grey water from the kitchen or dishwasher, as it contains food waste
  • Do not re-use grey water that contains cleaning products such as disinfectants or bleach
  • Do not use grey water on vegetable gardens if the vegetables are to be eaten raw
  • Do not re-use grey water that contains faecal matter such as from washing nappies.

As long as you take these simple precautions, grey water is perfectly safe and its re-use will not only save precious drinking water, but reduce your water bill as well. And most state governments offer rebates for installing a grey water diversion or treatment system, so there are plenty of good reasons for giving it a go.