A popular seller 525 litre SuDS System which is a combined 50% attenuation and 50% rainwater harvesting all in one tank.  Have an part attenuation system which reduces surface water build up and flooding and a rainwater harvesting part where you can collect and store rainwater. 

There are benefits to both but collecting rainwater and storing it can reduce the use of mains water and can be used in the garden which cuts back on water bills.

Having a SuDS system prevents flooding in areas of your garden giving the drainage system time to deal with the larger rainfall and not flooding.

The 525 litre water tank system is made using a high grade of plastic and comes with 3/4" raised brass threaded outlet and 2 x 1" brass threaded outlets, one on each side, ideal for draining the tank completely, connecting tanks together or connecting to an external pump. The water tank comes with a fully removable lid giving user full access.