Drainage Inspection Checklist

Verify pipe gradients meet Building Regulations (1:40 min for 100mm, 1:80 for 150mm)

Check all joints are properly sealed — no visible displacement or open sockets

Confirm bedding and surround material matches specification (pea gravel / concrete)

Inspect manholes for correct benching, channels and smooth transitions

Check SVPs are correctly positioned per layout drawing with fire collars where required

Verify air admittance valves are accessible and above the flood level of the highest fitting

Confirm CCTV survey completed and clear before backfill (report available on site)

Check connections to adopted sewer are approved, inspected and properly benched

Verify correct pipe diameter used for each run (100mm foul, 150mm combined)

Check that no drainage runs pass under load-bearing walls without lintel protection

Confirm all inspection chambers have correct cover strength for location (D400 for driveways)

Verify back-drop manholes are correctly constructed with rest bend at base

Check rodding eyes are accessible and positioned at changes of direction

Confirm surface water and foul drains are correctly separated (no cross-connections)

Verify soakaway / attenuation tank size matches design calculations and is correctly sited

Check rainwater downpipe connections are properly trapped where connecting to foul drainage

Confirm minimum cover depth over pipes is met (600mm under gardens, 900mm under drives)

Verify ACO / linear channel drains are correctly laid to falls with sealed joints

Check water test or air test has been carried out on completed runs and passed

Confirm gullies are correctly trapped, bedded level and set to correct height