Connecting to a mains sewer must be done properly. If the right sewer connections aren’t made, and household waste-water ends up in the surface water drainage system, rather than the mains sewer pipe, then pollution can affect our waterways and beaches. This impacts the environment, affecting wildlife, and potentially even posing a public health risk.

It’s estimated that 15% of rivers, and 9% of bathing waters, in England and Wales have failed water quality tests because of sewer misconnections (as these sewer pipe errors are called). Defra has estimated that somewhere between 150,000 and 500,000 homes in the UK may have some sort of misconnection.

Below-ground cross-connections are one way that surface water and sewage can mix, though misconnected appliances represent a significant proportion of sewer misconnections. Washing machines are the most common (35%), sinks (20%) and dishwashers (10%) come next, then toilets (5%).

How do I know whether my home has the right sewer connections?

Most often, sewer misconnections are found in urban areas, where modern era homes have been extended, converted, or otherwise modified. The clues to look for are:

• The property was built after 1920 – before 1920 homes were more likely to have ‘combined’ drainage, so a misconnection wouldn’t be possible.
• There are new manholes – this reveals that the drainage system has probably been altered in some way since the property was built. If you have any doubt, it’s best to ask a specialist to check whether this has been done correctly.
• There is an extension, garage conversion, new bathroom, new toilets, or new kitchen – errors (or tradesmen’s dodgy shortcuts) can mean that sewer misconnections can occur when new facilities have been plumbed in.
• There are pipes connected to rainwater downpipes – this is quite a big giveaway that waste-water is being misdirected into the surface water system rather than into a sewer pipe.
• There is an outside toilet, or a washing machine or sink, installed in an outbuilding – if these are plumbed in away from the main house, it’s more likely that they might have been misconnected to the surface water system, not the sewer pipe.

Whether through a householder’s genuine mistake during a DIY project, or a cowboy tradesman’s sloppy workmanship, sewer misconnections are a big deal. Misconnections where surface water run-off goes into the public sewer system are less commonly highlighted as a problem, but they still cause one – sewers can be overburdened during heavy rain, and this can contribute to leaking or cracking. With all this in mind, it’s no wonder that water companies are on the lookout for properties with misconnected sewer pipes, both to avoid damage to the environment, and to reduce the cost of sewer maintenance.

Who has responsibility for sewer connections on private land?

Misconnected pipes are illegal, as Section 109 of the Water Industry Act 1991 states that it is unlawful to discharge foul water into a sewer provided for surface water where separate public sewers are provided for foul water and surface water.

Where a sewer misconnection has been made on private land, then it is the responsibility of the property owner to put it right – fines can be thousands of pounds, so aside from being the right thing to do, there is a financial incentive to fix the problem.

To find out more about how we can help solve underground sewer misconnections, and for free advice on connecting to a mains sewer, call 01268 950050 or send us an email to [email protected].