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Harvesting Rainwater in Storm Water Management

The UK is a rich western country with a population of 60 million. Average water use is 150 litres per person per day (55m3 per person per year). Although the perception (not least by its inhabitants) is that the UK is a wet country with plenty of rainfall, the reality is that the UK only has 2440m3 of available water per head of population and is classified as a country with insufficient water.

As 98% of properties receive a main water supply, rainwater harvesting is seen as a means to reduce the demand on the potable water supply, rather than as a source of water in situations where no other source is available. In any sustainable water strategy, it is important to reduce water use within the building first before looking at alternative sources of water.

Surcharging of storm water drains is a problem that is exacerbated by intense rainfall and increasing development, this presents a significant problem especially to urban planners. Existing storm water sewers become overloaded and surcharge, causing localised flooding incidents. If the storm water discharges into a combined sewer then it causes foul water to mix with flood water, this has health implications as well as the potential to cause damage to property. Once a rainwater harvesting system is installed, rainwater from the site is diverted before it adds to the load on the storm water drainage. The rainwater is stored, used in the building when required and eventually enters the foul water stream.


An example of an urban area that has failed to install a proper rainwater harvesting facility

Reducing water demand at the point of use is important and has to be part of any sustainable water use strategy for the UK. Stricter control of the industry is vital if the UK Government is to successfully persuade consumers to reduce water demand. Rainwater harvesting can be a solution to these increasing water shortages.

Do you think the harvesting of rainwater is a sustainable and viable way of reducing water shortages and flooding problems in urban areas?

Credits: Photograph by Finbar Gillen. Data linked to sources