This system operates by collecting water from roofs, storing it in an underground tank and pumping it up to a feeder tank. More commonly an on-demand pump is used to supply water from the rainwater tank to wherever there is a demand for the water.

A rain harvesting system can provide water to replace up to 50% of mains supply for non-potable water use. Toilets, washing machines and garden watering can all use water from the rainwater system. The pipe work for rainwater should be clearly marked to differentiate it from mains supply.

Information on installing a system can be found with organizations like http://www.rainharvesting.co.uk  www.ukrha.org or www.wras.co.uk.