What are misconnections?

A misconnection is where a property’s wastewater is connected into the surface water network, or surface water drainage is connected to the foul sewer network.

Both of these types of misconnection cause sewage pollutions to watercourses, that can harm wildlife, the environment, and people.

A foul-to-surface water misconnection will allow raw sewage to go straight into a watercourse via the surface water outfall.

Surface-to-foul sewage misconnections, increase the volume of wastewater in the sewer, increasing the likelihood of property flooding, storm overflow events, and pollutions. 

Fact: Defra estimate that between 150,000 to 500,000 households in the UK are misconnected. 

What are we doing to stop misconnections?

found to be misconnected in 2023
> £150,000
spent on investigating misconnections in 2023
Up to 500khomes
suspected to be misconnected in UK

As part of our mission to stop pollutions and protect the environment, we are working hard to identify misconnections, so they can be fixed. 

To help us with this important work, please report any outfalls that appear to be polluting, for example, they're causing discolouration in the watercourse, or discharging sewage-related debris like toilet paper. We'll investigate based on these reports.

Report a pollution


Preventing misconnections

Misconnections can occur when a property is being built, when an extension is added, or when other modifications are made to a property's plumbing or drainage. 

If a misconnection is found at a property, it is often the responsibility of the property owner to resolve the misconnection, covering the costs. 

As such, to avoid this, it's important to use trusted traders for any work involving your plumbing or drainage. We've got a handy guide for you to use to find an approved plumber.

Find an approved plumber


When having work done that involves adding or changing connections on your waste or surface drainage, consider asking the tradesperson:

  • Have you double checked you are connecting to the correct sewer?
  • Do you know who owns the sewer you are connecting to? 
  • Are you altering or making a new connection into South West Waters sewer?
    If so you need to request the right to connect, otherwise the connection will be illegal.

Misconnections and tradespeople

It's important for tradespeople to consider the risk of misconnections. If they cause a misconnection at a property, the property owner could approach them for compensation.

We want to help tradespeople so that misconnections become a thing of the past. Our asset mapping can help them make informed decisions when working on or near a property’s drainage to avoid mistakes. 

The property owner can request free SWW asset plans for their property by emailing searches@southwestwater.co.uk.

Tradespeople can also request an asset plan, but there is a small cost for them:

If you're creating a new connection into to our network or altering an existing connection, don't forget, you need to request the right to connect, otherwise the connection will be illegal.

Need a plumber?

Check out our guide to choosing an industry approved plumber so that you can find one you can trust.

Need a plumber? image