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  • Anti flood Flap Valves for drainage and soil pipes available in two sizes 4" and 6" (110mm, 160mm)
  • How a Flap Valve works.
  • Flap Valve Installation example - at the end of a soil pipe in a chamber.
  • Dimensions of both the 110mm (left)and 160mm (right) Flap Valves

Flap Valve - Anti flood Non Return valve, Drainage Pipes


Prices include VAT


Product Description

4 inch and 6 inch flap valves for waste (soil), drainage and water pipes 

Non Return Valves for drainage and water pipes, available in two sizes 110mm and 160mm. Slips onto the end of pipes. Effective Anti-flood Valve and Rat Barrier Drain Protection.

These Flap Valves are sometime called "Outfall" Flap Valves as they are installed at the end of the pipe. We also sell Horizontal Inline Flap Valves for installation along the pipe.

What is a Flap Valve?

Flap Valves are innovative devices used to prevent flooding caused by the back flow of storm water and sewage. Backflow can be caused by intense rain, thaw or floods. The valves prevent backflow into residential and commercial premises via the drain systems, toilets or sewers. Effectively protecting rooms on lower levels against flooding caused by backflow of storm water and sewage.

Where the Flap Valve has a metal Faceplates (like these), they are also an effective rat barrier to your drainage system. The metal stops the rodents from chewing through the flap facepate of the non return valve and protects your plumbing system from rats and other rodents from entering buildings.

Flap Valves are installed on a pipe and allow water (and or solids if a soil or drainage pipe) to flow through the pipe as usual, but prevent anything from flowing back in, like flood water, rats or debris. The pressure of the water flowing through the pipe will open the valve, they automatically close when there is nothing flowing through the pipe.

Where can these Flap Valves be installed?

These flap valves are designed to be installed at the end of horizontal sewage pipes entering collection wells, cesspits or on drainage pipes leading storm water to soakaways or rivers. They are sometimes referred to as Outfall Flap Valves.

Available to fit either 110mm (4 inch) or 160mm (6") pipes.

Easy to install. The Non-Return Valve simply slips on to the end of the pipe. The O-ring within the Valve effectively jams the Flap Valve onto the pipe.


Unfortunately we cannot accept returns for this product when it has been fitted. If you are unsure as to whether this is the correct product for your system, please contact us before purchasing. We will happily offer free, impartial advice.

Technical Information

This flap valve is equipped with a chromium-nickel cover (A) protecting the flap and gasket. Additionally a chromium-nickel cover of the lever (B) has been designed into the Non-Return Valve to protect against rodents, atmospheric and the environmental conditions (eg. river flow). Flap valves have a rubber O-ring on the inside which ensures a tight fit of the valve to the pipe and effectively keeping the valve in place.

  • Suitable for water, drainage or soil pipes
  • Fits either 110mm or 160mm Pipes
  • Fits over the outside of the pipe
  • Installed at the end of the pipe
  • Operation fully self-activating
  • Plastic body: high quality polypropylene with increased UV resistance. The material is harmless to the environment and can withstand temperatures up to 95°C as well as resist aggressive chemicals.
  • Stainless chromium-nickel stainless steel Faceplate
  • Conforms to EN-13564-1:2004

Other Versions

Product Reviews

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  1. 110mm Flap Valve 5 Star Review

    Posted by on 19th Aug 2020

    Ordered these valves for open pipe ends on a surface water drainage project.Great value and quality.My customer was most impressed.
    Delivery time was very good and Celtic Water emailed as the order was processed through to delivery.
    Many thanks.

  2. Excellent product 5 Star Review

    Posted by on 18th May 2020

    Very happy with the product, has solved the problem with my field drain, when the brook floods the water now will not run back onto the field. Good prompt service, arrived very quickly. Impressed with product and service.

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