What’s a combined rainwater harvesting and stormwater tank?

Posted by Callum Vallance-Poole, on October 12, 2020.

Living in the UK means dealing with a fair amount of rain each year. Depending on where you live it can also create flooding issues, but with the right equipment this can be prevented and the rain used to your benefit around the home. In this article we explain how a combined rainwater harvesting and stormwater tank can help.

What is a rainwater harvesting tank?

A rainwater harvesting tank is able to collect and store rainwater that falls onto the roof of your home via a small device that connects to the gutter downpipe. The collected water can be used for watering the garden and is a much more organic and healthier option than using tap water, as it is lower in acidity and contains everything plants need to thrive. The stored rainwater can also be used for many chores around the home, such as cleaning the car and flushing and cleaning the toilet. 

What is a stormwater tank?

A stormwater tank is used as a protective measure to control the disbursement of water away from your home after a heavy period of rain. They remain empty for long periods so they remain ready to take in rain during wetter periods of the year. A key part of their design involves the use of valves that slowly release the water out of the tank. The idea behind this is not only to prevent flooding occurring in and around your home, but also in other areas once the rainwater attempts to drain away.

What is a combined rainwater harvesting and stormwater tank?

By combining a rainwater harvesting tank and a stormwater tank into one you get a more cost effective way of managing rainfall around your home. You are still able to efficiently harvest rainwater to be used as and when needed, while also benefiting from the floodwater management provided by a stormwater tank. This sort of product is referred to as a retention system.

What sort of retention systems can you buy?

GRAF have a number of retention systems designed for a variety of different needs:

  • Platin XL – This retention tank can hold either 4,900 or 7,500 litres (the XXL size expands this to up to almost 30,000 litres). Depending on requirements, a delayed drain of 0.05 to 2.0 l/sec can be installed. A floating drain choke is used to delay the speed of water drainage into the channel during period of heavy rainfall.
  • Platin – Offers a storage size between 3,000-7,500 litres using the same system as the Platin XL to effectively manage the drainage of water. If more specialised solutions are required, GRAF are also able to construct and supply these where needed.
  • Carat S – Store 3,750 to 6,500 litres of rainwater for harvesting and/or stormwater management. Uses the same system as our other retention tanks and also offers frost-proof installation underground.
  • Carat XL – Choose a tank that can hold either 8,500 or 10,000 litres of water and enjoy a 15-year warranty (as standard on all our tanks). An XXL version of the Carat model is also available, offering retention of up to 122,000 litres of rainwater. 

Marketing Coordinator - Based at our UK HQ in Banbury, Oxfordshire, Callum is responsible for promoting Water Management Systems, Attenuation Tanks, Treatment Plants, Rainwater Harvesting Systems and more!