In our day-to-day living of getting up, having breakfast, going to school, eating lunch and tea, washing ourselves, clothes and dishes, etc., we each use 140 litres of water a day, on average. The greatest contribution to this usage (30–40 per cent) comes from the flushing of the toilet to get rid of our bodies’ waste. It seems odd that water is purified to a stage where it's fit to drink and then most of this good quality water is flushed down the loo! In the UK, the modern WC cistern holds 9 litres (2 gallons) but there are plenty of houses with cisterns of 13.6 litres (3 gallons) capacity. In recent years there have been concerns about water shortages in summer because of drought. One way of reducing water shortages is to cut back on our water usage, and this could be partly achieved by reducing the capacity of the WC cistern. In 1996, the House of Commons Environment Committee recommended that people should be encouraged to replace their cisterns with ones of 6 litres capacity. There are also devices now available that can be plumbed into houses to collect ‘grey water’ (water that comes from washing machines and sinks). This is partly purified and pumped to a storage tank in the roof from where it can be used to flush toilets.

Apart from the WC, the average water consumption, in litres, for different uses in the home is:

In addition to the water that is used by ourselves in our homes, the drains also receive the water used by industry and, on average, this amounts to the equivalent of about 300 litres per head per day. Whatever product is being made in a factory, there's almost certainly wastewater being produced which needs to be purified.