<P> Rainwater harvesting was being encouraged by the government of the UK through the Code for Sustainable Homes . The code ranked homes on a scale of one through six and requires new homes to have a score of at least three . One way to raise the score of a newly designed home is to incorporate a rainwater harvesting system . The code was revoked in 2015 . </P> <P> The Environment Agency has noted that water resources in the UK are under increasing pressure because of the growing population . In addition, the agency has warned that the South East of England is facing more serious water scarcity than anywhere else in England or Wales, such that the per - capita water supply is lower than many Mediterranean countries . The agency encourages a two - pronged approach to both reduce demand and increase supply, such as through the use of rainwater harvesting . However, there is a fundamental mismatch between supply and demand; the areas of the UK suffering water scarcity are in most cases also areas with low rainfall, which means the economics of installing a domestic RWH system are less favourable . The environmental impacts of domestic RWH systems are questioned since the environmental impact of water supply is a very small proportion of the total impact of water use (approximately 4%). For a UK household, the CO impact of supplying water to the house is around 100g of CO per day, around 1 / 600th of your total daily impact . However in countries without widespread mains water supplies, or where the environmental impact of mains water is very high, RWH may have more merit . </P> <P> The installation of rainwater harvesting systems in the UK should be done according to the Water Supply (Water Fittings) Regulations and BS8515, in order to ensure safety . BS8515 also provides details on how to size the storage tank and allows estimation of the potential water savings . If you install a RWH system, you will need to inform your water company . </P> <P> Rainwater harvesting at large scale may well be appropriate for farms as part of a catchment management strategy to decrease flood risk and diffuse pollution . </P>

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