Drainage Misconnections

“We have been completely happy with the service provided and would happily use Act again, in fact, we may well be in touch some time soon!”

– Residential Homeowner, Mr Tomlinson

How Surveyors Identify the Problems

In many parts of Britain, serious pollution is caused by drainage misconnections. People do not understand there are different types of sewerage systems, for clean and for waste water; just over half of all properties in the UK are served by separate sewers. Sinks, washing machines, baths, showers, toilets and even whole houses or streets can be incorrectly connected to surface water sewers that discharge untreated sewage directly into rivers and beaches.

Pollution is also caused when clean surface water drainage from roofs and paved areas is connected to foul or combined drainage systems. So-called ‘clean misconnections’ cause increased pumping and treatment costs, take up sewer capacity and overflow into rivers and sometimes properties in periods of wet weather. This was particularly evident with the intense rainfall experienced in summer 2012.

Most above ground misconnections are relatively easy to spot, but surveyors also need to be aware of the possibility of blocked, damaged or leaking drains below ground. Below-ground drainage problems can lead to structural problems, cause groundwater pollution and capacity issues in wet weather.

Once identified, the responsibility to rectify drainage usually rests with property owners. While most misconnections are fairly simple and cheap to fix, some below-ground problems can be more complicated and expensive. With the transfer of private sewers, most below-ground sewers serving more than 1 property are usually now the responsibility of water companies. Building control approval checks for new developments are also important to ensure that drainage is installed properly and connected to the correct type of sewer.

The responsibility to ensure that misconnections are addressed is divided between:

Local Authorities: under section 59 of the Building Act 1984, they have the power to serve notices to ensure drainage is effective and under section 79 and 80 of the Environment Act 1995 they can also address a statutory nuisance.

Environment Agency: has an overall duty to protect water quality and can serve Anti-Pollution Works Notices under section 161 of the Water Resources Act 1991 to rectify problems and/or prosecute polluters.

Water Companies: as owners of many surface water sewers, they have a role to investigate misconnection problems and pollution in their assets. The UK has to ensure ‘good ecological status’ for all designated watercourses by 2020 under the Water Framework Directive (WFD) and the Environment Agency is now working with many organisations to achieve this. For city dwellers, urban rivers and streams can be one of the best ways to interact with the natural environment. Studies have

shown that access and proximity to green spaces can impact positively on property prices and people’s wellbeing.

Meanwhile, many of the UK’s beaches are designated and monitored under the EU Bathing Water Directive. It is estimated that misconnections impact on 9% of such beaches and 15% of WFD water bodies. They also threaten shellfish, water quality and compliance with bacteriological standards.

In much of the south and east of Britain, the majority of drinking supplies come from groundwater, which can be impacted by leaking sewers. As well as the obvious risk of disease, sewage contains a range of pollutants, including nutrients that affect ecology, oxygen depleting substances and harmful chemicals used in everyday products.

Scale of problem

A UK Water Industry Research project recently estimated that there are up to 500,000 misconnections across the country, but this is perhaps a conservative figure. Investigations by water companies find an average of 2.3% properties are misconnected, but in some networks this is far higher.

Misconnections can be very common in properties of a particular age, such as post-war semi-detached properties on new estates with separate drainage systems. They can also be found in newer properties where the macerator pumps now available make installing an appliance or a toilet possible where waste water could not previously be drained.

RICS surveyors undertaking home surveys need to check drainage systems to identify any potential misconnections, particularly where there are separate systems. This will usually only require a low level of awareness to spot obvious above ground pipework but may include dye testing and more in-depth CCTV surveys for some properties.

A Certified Drain Surveyor scheme has been developed by the National Association of Drainage Contractors, the Environment Agency and Water Research Centre. The Energy and Utility Skills registered course trains and certifies drainage contractors who work on domestic properties and light commercial sites.