How do attenuation tanks work?

Stormwater attenuation tanks are ideal if you’re looking for a bespoke and cost-effective solution to control the flow of water back to a watercourse or drainage system. They are commonly used for larger commercial applications.

Here we take a closer look at attenuation tanks – covering what they are, what they’re used for and how they work.

There’s no denying that attenuation tanks and soakaway crates use the same core products, however, they remove water in very different ways.

Simply put, a soakaway ‘soaks’ water back into the soil whilst an attenuation tank holds and redirects it to another place.

Stormwater attenuation tanks provide a storage system for rainwater and surface water. The stored water inside the attenuation tank is released via a flow-control chamber and is either pumped via a pumping chamber or run-off through a gravity stormwater pipe system. The surface water run-off is slowed down before it is discharged into the local watercourse (i.e. a river or reservoir) or sewer system, effectively reducing the risk of localised flooding.

Legislation has put a lot of pressure on local planning authorities and specifiers to implement systems to prevent flooding. The idea is to design a system that can deal with the flow at the source – rather than downstream – but, in the meantime, a stormwater attenuation tank will do the job just fine.

This is an alternative to soakaway crates or an elevator. Where the previous two methods of storm attenuation simply catch water from their surrounding area, a separate tank has the ability to capture water from a very wide area using connected pipes and collect it all together in one huge tank for distribution.

They are generally preferred on larger commercial applications because they can be quicker to install than other stormwater attenuation systems.

The way an attenuation tank works is simple.

It is designed to collect the excess rainwater and hold it back temporarily. The beauty of such systems is that they have a flow-control chamber that controls the amount of water being pumped into the drainage system – releasing it at a rate that the infrastructure can cope with.

During periods of heavy rainfall, the water that would be typically backing up is fed into the crate system and held in the stormwater attenuation tank until it is ready to re-join the main system. It is then returned to the watercourse, at a regular rate, to prevent flooding downstream.

What are the benefits of installing an attenuation tank? 

There are many benefits to installing an attenuation tank, which makes it great value for money.

Firstly, this system will significantly reduce the risk of flooding, as the stormwater is retained and released at a manageable rate through a flow control chamber. This will also help new developments reach the Sustainable Drainage System (SuDS) requirements. The prevention of flooding is beneficial in terms of protecting the environment, as not only does it prevent damage to houses and buildings, but it also protects the local wildlife and ecosystems too. 

Installing an attenuation tank will be cost-effective in the long-run, due to a significant reduction in costly repairs from damages caused by flooding. This includes infrastructure repair, environmental restoration and overall flood damage.

An attenuation tank will also lower the burden on local sewage systems, due to stormwater being contained and controlled. This is opposed to surface water causing a strain to local sewerage systems.

Due to the ongoing effects of climate change, now is the time to invest in a stormwater attenuation tank, for the protection of local communities and the wider environment. 

Want to know more?

Here at Cotterill Civils, we don’t just supply a range of stormwater attenuation solutions, including soakaway crates and stormwater attenuation tanks, we design and install them too. If required, we can also install your system for you – providing you with the peace of mind that it’s installed correctly – and will be more than happy to offer a bespoke solution to suit your requirements.

If you would like to know more about our stormwater attenuation tanks and how they work, please feel free to call us for expert advice on 0121 351 3230.