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T-T Flap Valves for £5million Matlock flood defense

River Derwent running through Matlock, Derbyshire.

In early 2022 the United Kingdom was struck by several intense storms in quick succession - this led to flooding and structural damage across many parts of the nation. Matlock, in Derbyshire, experienced severe river flooding, causing the collapse of a wall and water damage to nearby properties.

Following this, a plan to improve the county's flood defences and further protect 50 homes was put in place - including high-quality valves and T-T Flow.


The project required several double hinge flap valves suitable for outfall applications - outfall being the control of water from a drainage system (a storm drain) to a receiving body of water (a river) to prevent flooding. Precise outfall system design is crucial for effective stormwater management - the purpose of the non-return valves is to prevent the reverse flow of water and debris from the adjacent body of water back into the outfall, as this can cause storm drain flooding, environmental contamination and local water quality issues.

The Solution

The T-T Flow team selected 7x DN100 and 3x DN225 double hinge flap valves for the application.

These non-return check valves were created with stormwater applications in mind - constructed from ductile iron for a high level of durability (with a scalloped design for reduced weight) and increasing their longevity in an application susceptible to high-pressure water flow. The double hinge design gives the flap valves greater stability than a single hinge, making it less prone to misalignment and ensuring a reliable seal to prevent backflow. Potential backflow is further reduced by the seating faces of the valve, where the sealing occurs, being precision machined to provide the tightest seal possible.

With a maximum pressure capability of 6.0 metres static on-seat head and corrosion protection coating (blue, fusion-bonded epoxy), these flap valves can endure the high levels of water flow expected from the application, continue to operate reliably and still look aesthetically pleasing.

Reliable, long-term flap valves from T-T

T-T Flow knows that the features of the valves they provided for the flood defence scheme make them robust and reliable, which is vital to the new flood prevention measures working effectively.

View T-T's range of valves and accessories here - or talk to one of our team for expert advice on valve selection +44 (0)1630 647200