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5: sustainable architecture 17
Rainwater
Rainwater is a free resource which every building should use. The cost of installing rainwater recovery systems can be paid back in less than 10 years. High quality filters and low energy pumps deliver clean water to flush toilets and feed washing machines. With care rainwater can also be fed into the hot watervsystem for washing.
Rainwater recovery is possible on any building but the amount varies according to the porosity of the roofing. Natural clay tiles absorb more than metal sheet. Between 70 and 90% of the rainwater falling on a roof can be collected for re-use. It is soft, but can slightly acidic owing to atmospheric pollution so care should be taken not to use copper pipework.
Rainwater storage can be above ground in low cost containers like the one illustrated above, or in underground tanks which hold a lot more water and keep it cooler and fresher. Underground tanks can require concrete to hold them down, so care needs to be taken when selecting your system.
