Help & Advice

What is grey water?

Grey water is wastewater from showers, baths, and wash basins. If treated correctly it can be used for flushing the toilet, watering gardens and washing cars, helping to cut down water consumption by more than a third.

The use of grey water technologies in our homes is still in its infancy. This is because the cost of fitting such systems is high and there are concerns the quality of the water may pose a health risk.  While grey water from baths, showers and basins is usually clean enough for flushing toilets, bacteria can soon build up when nutrient rich waste water is left untreated for a period of time. To prevent bacteria levels from building up it is advisable to only have a small storage tank, which in turn can cause problems for providing a reliable supply during periods of low rainfall.

Grey water recycling systems can now be purchased from many outlets such as DIY stores.

Larger grey water systems that supply more than one property tend to use more sophisticated "biological" treatment methods. This works in a similar way to the processes used at sewerage treatment works. Small-scale systems tend to use "physical" treatment methods which rely on a basic filtration process. They tend to require the use of chemicals similar to bleach to stop the growth of bacteria while the water is in storage. Some systems use a combination of the two giving a "bio-mechanical" process.


All installations must comply with the Water Supply (Water Fittings) Regulations 1999 and the Building Regulations (parts G & H).

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