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What is rainwater harvesting?

An example of a rainwater harvesting systemRainwater harvesting is the process of collecting, filtering, storing and using rainwater. One of the most common forms of rainwater harvesting is from rooftops.

Why should rainwater be harvested?

Did you know that rainfall per head of population in the south of England is lower than it is in Mediterranean countries? This makes rainwater a vital resource, which we should aim to reuse as much as possible. Rainwater harvesting systems save large amounts of water and can therefore also save large sums of money.

A single roof collects around 85,000 litres of water a year. According to the Energy Savings Trust (EST), this is the equivalent of filling 450 water butts! Aside from the environmental benefits of reusing rainwater, it is estimated that up to 50% of savings can be made on annual metered water bills by harvesting rainwater. That’s an excellent incentive for any property owner!

What is a rainwater harvesting system?

A rainwater harvesting system is connected to a property’s water mains and guttering systems. An underground tank collects rainwater, passing it through a filter to collect leaves and debris.

The system is sunk into the ground, which ensures that the tank remains cool and dark. A steady inflow ensures that sediment isn’t stirred up. These features contribute to high water quality.

How a rainwater harvesting system worksIf the tank level gets too low, a control system tops the tank up with mains water. Excess water is drained into the sewage system or infiltration system via an overflow siphon. A rainwater harvesting system is designed to overflow, as this can help to keep the filter clean.

When there is persistent rainfall, a soakaway or storm drain setup is recommended to handle this excess. Note: the UK Rainwater Harvesting Association states that there is no direct requirement for rainwater harvesting from building regulations, but regulations may be linked with the storm water management system of the site.

What is rainwater harvesting used for?

Once harvested, filtered water is then delivered via the supply network. Harvested rainwater can’t be used as drinking water, however it can be used for grey water purposes. Rainwater can therefore be reused for washing clothes, watering gardens and flushing toilets.

Here at Drainage Superstore, we supply a wide range of rainwater harvesting systems from leading manufacturers such as Graf and Marsh Industries. Call our helpline on 01752 692 221 for expert advice on these systems, or use our live chat facility.


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