Toilet flushing uses 35% of domestic water

Typically, every household uses about 50 litres of water per person per day for WC flushing. This represents about 35 per cent of all domestic water use. The most efficient WCs can reduce this volume to around 20 litres or less per person per day.

Although the manufacturers make nominal nine, seven-or six-litre WCs, each flush uses more than this amount, mainly because, as the toilet flushes, it immediately starts to refill. A new, patented water cistern inlet valve addresses this problem. It has a small delayed evacuating bowl beneath the float that operates the valve. When the WC flushes the water level in the cistern drops but the valve is held shut by the water remaining in the bowl. As the water drains slowly, the valve can open and the cistern can refill. When used with a seven-litre WC the valve can save about 1.4 litres per flush at 3-bar and 3.5 litres at 10-bar, when compared with the same valve without the bowl.