Collecting rainwater for non-potable use — and keeping the wholesome supply protected.
Rainwater harvesting collects rain (usually from the roof) for non-potable uses such as WC flushing, the garden, or a washing machine — reducing mains water use.
The system. Roof → filter → storage tank → pump/feed to the non-potable outlets. An overflow returns excess to the drainage system.
The critical safety point. Harvested rainwater is not wholesome — it must never cross-connect with the mains supply. Any top-up from the mains must be through a suitable air gap / backflow protection (a high fluid-category risk), and all non-potable pipework and outlets must be clearly marked to prevent anyone drinking it.
The Water Supply (Water Fittings) Regulations govern this protection and marking. Greywater reuse follows the same principle with additional treatment.
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