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Underground FAQs

Yes, they have a double sealed lid and can be installed in garages.

Yes, our underground drainage system is to EN 1401 and sewer system is BS5481.

Shallow Inspection Chambers can be installed to 600mm, which is 2 risers high.


For the 280mm chamber there is a lid for pedestrian areas (B2802).  For 315mm chambers there is lid for pedestrian areas (B3153) and another for driveways (B3154) which is rated to 35kN. For 450mm chambers there is a lid suitable for driveways (B6255) and is rated to 50kN. 

You can either use an adaptor to the top of the pipe (B4301), (B4501) or a hopper (B1031) with the waste going into the top.


Yes part no. B3500 is the adaptor required.

For 110mm drainage the gradient is 1:80 with 1 WC. For 160mm drainage the gradient is 1:150 with 5 WC’s.

Yes there are a choice of Back Inlet Roddable Gullies with 90° Outlet available to choose with choice of grid:  with Round Grid (B1001); with Rectangular Grid (B1002) and with Square Grid (.


An inspection chamber should be installed at each change in gradient, direction or pipe size.