backwater non return valve or nrv are fitted to storm drains and underground sewer pipes to prevent the backflow of waste and dirty water and effluent sludge in the event of storm water overflowing the system and resulting in a flood situation.
nrv come in all different sizes and can be as small as 15mm and moving through the range to 600mm once liquid has passed threw them it cannot return because of the flap valve built into the body of the backwater non return valve.
pvc in construction with stainless steel flaps and screws and rubber seals on the internal body backwater non return valves are robust in construction. any of the nrv can be locked shut via a switch mechanism on the outer body of the backwater non return valve , this enables work to be carried out on the rest of the underground drainage or sewer system safe in the knowledge that water sewage and effluent drainage water cannot escape the system whilst work or repairs are being carried out making backwater non return valves a very health and safety conscious peice of equipment.
the prevention of flooding to all of us is essential and the protection of property is high on every ones mind, every house in the country can be fitted with a backwater non return valve between there sewer line and the first manhole inspection chamber on there property, this work can be done by your local builder or drainage contractor or can be a diy project, when fitting a backwater non return valve it is always best to install it in its own chamber so you can access the lock off lever on the body of the nrv. the tops of the nrv are also removable so in the event of a blockage you can clean the internal flap valve and keep it free of grease and dirt that may build up in your drains.