Non-potable reuse of rainwater championed in new sustainable drainage standards

Defra stopped short of mandating the use of sustainable drainage systems when it issued new national standards last week.

That disappointment aside, the seven new national standards have been widely welcomed as a positive refresh, offering clearer guidance and supporting consistency in both new builds and retrofits.

The standards encourage features such as green roofs and soakaways, and, importantly, spaces designed to collect and filter rainwater for non-potable use in industrial, commercial, horticultural, educational, public sector, residential and multiple-occupancy building settings.

In fact, the guidance establishes collecting rainwater for non-potable reuse as the new top priority in the national drainage hierarchy, ahead of infiltration to ground or discharging to watercourses/sewers. The standards champion rainwater harvesting being considered in all circumstances where: there is a demand for non-potable water and available contributing catchment area that will deliver safe and efficient water savings; where there is a need for landscape irrigation; and where development is in an area identified as seriously water stressed.

Among the benefits of following the new standards are: greater water efficiency, reduced flood risk, improving water quality before it enters watercourses, supporting biodiversity and boosting amenity space.

The updated standards are aligned with the National Planning Policy Framework and will complement wider planning reforms which will take place later this year.