WaBack is an "all in one" installation that works as both as an inspection chamber and as an automatic non-return valve.

The solution is available as standard for pipe DN110-315.

The WaBack non-return chamber is also available with an access chamber, allowing easier access from ground level. The product is then called WaBack Access. 

Click to read more and to see animation - https://wapro.com/en-gb/products/waback-non-return-valve