Grey water (or gray water) is neither fresh nor polluted water and must be distinguished from black water, a term used for dirty water, i.e. sewage water and water with high concentrations of toxic chemicals or wastewater containing significant food residues.
Typically a grey water system recycles water from baths, basins showers and washing machines to irrigate lawns and gardens.
In the traditional sense grey water is fed through a filter to a pump chamber where the water is automatically released via a drive pipe to a garden sprinkler system. An average household in South Africa could expect their water bill to reduce by around 35%.
Garden irrigation is however not the only use for grey water; it can also be used to flush toilets.