Storm sewers vs foul sewers – what is the difference? September 19th 2018, by Ian Lishman

What is storm water and what is foul water?

Storm water is simply rain and surface water. It should be uncontaminated and can therefore be discharged into the ground via a soakaway, or into a watercourse. Foul water is waste water from the kitchens, bathrooms etc of buildings, which discharges into the drainage system to be carried to treatment plants.

What is the distinction between drains and sewers?

Typically, a drain is considered to serve a single property, while a sewer serves multiple properties across the whole site. The storm and foul drainage from each plot feeds into the mains sewers.

Is storm and foul water always separate?

Some old properties still have combined drainage, where storm water and foul water are removed from the site together and all sent to water treatment. On all new sites, the two drainage types are separate, reducing the burden on water treatment and allowing clean water to be returned to the environment.

What is a cross-connection?

In the event of a storm water drain and a foul water drain being connected when they should be kept separate, a cross-connection is said to have occurred. Storm water draining into a foul drain or sewer is like a combined drain.

Foul drainage discharging into storm drainage, however, contaminates clean water and can pollute a watercourse. Such a situation can result in expensive remedial works and, depending on the scale of pollution, fines as well. Working with a civil engineering contractor who can deliver drainage works without errors on that scale gives housing developers reassurance and peace of mind.

About FACE

For nearly two decades, FACE have delivered high quality civil engineering works on projects of all sizes. Our new turnkey service allows housing developers, whether small or large, to work with us and build a project-specific package of services that FACE then delivers.

The package can include highway works carried out under a section 278 agreement, drainage construction and groundworks. Acting as a single point of contact for multiple aspects of the infrastructure means we can offer improved coordination of works and minimise potential delays.

Find out more and enquire about our turnkey packages here.