Sewer flooding is extremely unpleasant and can cause significant damage to your property and possessions, as well as result in emotional distress. However, sewer flooding is often overlooked when considering sources of property flooding and is an occurrence that may be far too familiar to some.

Although not a direct result of natural sources of flooding, sewer flooding events generally occur when the sewer system becomes overwhelmed from heavy flash flooding, collapsing drains or as a result of blockages caused by the inappropriate disposal of everyday waste, most notably toiletries and kitchen waste. Sewer flooding incidents can either be internal, where waste water enters your property through toilets or sinks, or external, where waste water from external drains floods the grounds of your property.

Damage from flash flooding and overwhelmed sewers costs up to £260m a year, and this figure is expected to rise as a result of climate change, increased extreme weather events, and the demand for new housing. Large residential developments are being connected to existing drains, putting extra stress on the public drainage systems. This, together with the reduction in permeable surfaces from new houses and driveways, can lead to increased surface water flooding and sewer flooding.

As a result of these incidents, even if flood risk may have been addressed from other sources such as surface water flooding and river flooding, sewer flooding from surcharging sewers may occur at associated manholes or at nearby properties, resulting in a less than pleasant scenario for a vendor.

Insurance companies may cover costs of any damage and clean up, however actions by the vendor themselves can reduce the potential for internal flooding at the property if such an incident was to occur. Such alleviation provisions include fitting non-return valves in the sewer pipes, disconnecting cellar drainage for internal incidents, fitting UPVC doors and fitting air brick protectors if flooding is initially outside the property.

It is also important to ensure that drainage has been considered as part of a new development, both for the developer and the future occupants. Sustainable drainage systems (SuDS) may have been incorporated as part of the development. SuDS try to replicate natural systems to drain away surface water run-off through collection, storage, and cleaning before allowing it to be released slowly back into water courses. There are many different methods for doing this such as swales, attenuation basins and permeable paving, and the best approach for each site will depend on the overall flood risk, nature of the site and type of development.

If you are looking to purchase a property, or would like to know more about surcharging sewer events in your area, contact your local water and sewage provider and request a postcode search of recorded events. Dependent upon your water and sewage provider, there may be a small fee for this search to be conducted. Please see the CON29 website for your provider’s contact details.

If you would like more information on Sustainable drainage strategies for your development Sites in England or Wales please contact us at for a free quotation.

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