Non-return valves and backwater valves are a simple, cost effective solution to protect properties from flooding.
Non-return valves are installed to the inside of the manhole. These are fully automatic and they stop backflow of sewage into a property.
As surcharge occurs, the float rises and closes the valve. This isolates the property from the sewer. During surcharge inside the sewer, the valve is forced shut preventing backflow into the property. Significantly the valve still allows normal flow out from the property. When the surcharge has passed, the valve automatically opens.
There are 2 million properties at risk from flooding in the UK. Many of these will be from rivers overtopping or from surface water. Also there is a high risk of being flooded from the backflow of sewage. This is caused from severe rain storms, breakdown of pumping plants and blocked pipelines.
Most of the UK sewerage network was installed during the Victorian era. This was before flushing toilets, washing machines and daily bathing became the acceptable practice. The pipe system put in place then is not able to cope with this increased volume. Most of the rainwater falling on roads, paths and patios is now carried away from urban areas with the sewage by the same overloaded trunk sewers.
Backwater valves are fitted directly to the pipe. The valve contains a flap that allows water to exit the property, but closes to prevent the back flow into the property.
There are many types of non-return valves and backflow valves. These can be assessed in a full site survey and the correct measures for your property can be advised.