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  • Backflow Prevention Valve for fitting to Sewage Pipe
  • In-Line Backwater Prevention Device with Built-in Rat Barrier
  • Backflow Valve with Lockable Lever
  • Backflow Valve with Smooth Interior
  • Backflow Valve showing installation in Plastic Inspection Chamber
  • In Line Backflow Valve showing installation in Concrete Inspection Chamber

Inline Backflow Valve - Anti Flood Non Return Valve, 110mm, 160mm, 200mm


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Product Description

Non-Return Valve for 110mm, 160mm and 200mm Drainage Pipes

These Drain Non Return Valves (NRVs)/ Backflow Prevention Devices (BPDs) protect buildings against flooding from back flow of storm water and sewage travelling back up the sewerage, drain or toilet systems during intense rains, thaws, or floods.

Suitable for Drain/Sewage Pipes as well as Water and Rainwater Pipes. The simple and effective design also inhibits unpleasant smells from the sewage or drainage system.

KARMAT backwater valves are equipped with a manual closure lever. Changing of the lever from OPEN position A to CLOSED position B causes a complete arrest of sewage backflow. The interior of the non return valve is smooth ensuring non-interrupted flow of sewage through the device.

The flap guard (as well as all assembly elements (screws, nuts, washers)) are made from corrosion resistant chromium nickel giving effective protection against rats and other rodents.

The backflow valves can be installed in horizontal pipes within the building or in manholes/access chambers outside the building.

Available in three sizes: 110mm, 160mm, 200mm

How does the Backflow Valve Work?

The Backflow Prevention Device has a Single Flap that allows sewage to flow through it from one direction, but the flap closes tightly shut when sewage or water pushes at it from the other direction. This simple mechanism ensures that, during flood events, basements and rooms located at lower levels are protected from sewage from the sewer system. It is a fully automatic operation that requires no external power supply and includes a lockable lever for emergency lockdown of the pipe network or for maintenance.


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

  • Body Material: High Quality Polypropylene
  • Single Flap design (contact us for Double and Triple Backflow Valves)
  • Flap Guard Material: Corrosion resistant chromium nickel
  • Screws, nuts, washers: Corrosion resistant chromium nickel
  • Gasket Material: Rubber
  • Self Operating (Automatic) Mechanism with Lockable Lever for emergency closure
  • Suitable for Horizontal Sewage Pipes as well as Water and Rainwater Pipes.
  • Maximum operating temperature 95°C
  • Maximum operating pressure 0.5 bar
  • Meets BS EN13564-1:2002
  • CE Mark

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