The problem of misconnections
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Around 300,000 UK homes are sending wastewater from washing machines, sinks, baths and even the toilet direct to their local river instead of to the sewage treatment works. This is caused when mistakes are made in the way in the way that waste pipes are connected around our homes.
What's the problem?
The pollution resulting from misconnections can have a dramatic impact on rivers. It can bring visual and odour nuisance and cause health risk due to the levels of untreated sewage. This pollution impacts on the ecology of our streams and rivers, effects their use and can bring failures in bathing water standards.
Who is responsible?
Homeowners are responsible by law for making sure their waste pipes are properly connected – even if they did not carry out the plumbing that caused the misconnection. In rented properties, the landlord is responsible. Fixing the problems is often straightforward and not too costly.
Homes built in the 1960s and 1970s are most likely to have waste pipe misconnections.
Advice on misconnections and how to address them is provided on the ConnectRight website. This includes useful links and answers to frequently asked questions. Local water companies also offer advice to their customers.
What kind of misconnection?
There two main types of drainage from houses...
A combined network
In a combined network, foul waters (from our sinks, washing machines and toilets) and surface water (caused by rain) drain into one ‘combined sewer’. In normal weather conditions all these flows drain to the sewage treatment works. However, in extreme wet weather, to prevent flooding, overflow ‘valves’ operate and send the rainwater and diluted sewage to watercourses.
A separate drainage system
In the separate drainage system two pipe systems exist, a ‘surface water’ one for clean water and a ‘foul’ one for dirty water. Surface water sewers carry rainwater from paved surfaces and rooftops directly to local rivers and streams. This wastewater is untreated.
Separate foul water drains carry domestic grey water (from sinks and washing machines) and sewage to the foul sewer and on to the sewage treatment works. The wastewater is treated before it can be safely returned to rivers and streams.
In this type of split system, wastewater (grey water) from white goods, showers, baths and toilets should all go to the foul sewer.
... and 2 kinds of misconnections
A plumbing misconnection means that the domestic wastewater pipes are wrongly connected to the surface water drain. This is the main kind of misconnection that occurs. Any misconnected wastewater, from toilets, sinks, baths, showers, washing machines and other white goods will drain along with the rainwater directly into a local river. This causes pollution of rivers and streams.
Sometimes the domestic surface water pipes (roofs and gutters) are wrongly connected to the foul sewer. When it rains, the foul sewer may become overloaded with the rainwater and cause flooding.
An Olympic-sized problem
The water industry estimates that misconnections cause a daily sewage discharge to streams and rivers equivalent to all the foul waste produced by a town the size of Swindon (or about enough to fill 16 Olympic-sized swimming pools).
Good practice and information for homeowners
Together, the water industry and the Environment Agency have published good practice advice to help tackle the problems associated with misconnections.
Through the Sewer Network Action Programme (SNAP) and local water company campaigns, the industry is also raising awareness to help people tackle the problems of waste pipe misconnections in their own homes.
Best practice
ConnectRight
Online advice for households
How to deal with misconnections
Useful diagrams and handy hints
Investigation and rectification of drainage misconnections
Water UK/Environment Agency good practice document
pdf 233K
Misconnections from domestic properties
Water UK press release 25/01/10
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