Blocked inspection chamber or manhole — how to clear it

An inspection chamber (manhole) is an access point built into your drain run, allowing rods to be inserted to clear blockages. If you have a blocked drain inside the house, the first step is to open the nearest inspection chamber and see whether it is full.

Locate your inspection chambers — in most properties there is one near the house and one near the boundary. Use a manhole hook or flat crowbar to open the cast iron or plastic lid. If the chamber is full of sewage, the blockage is downstream; if empty, the blockage is between the house and the chamber.

For a downstream blockage: assemble drain rods (screw them together firmly — a disconnected rod in the drain is a much bigger problem). Fit a rubber plunger or corkscrew attachment to the first rod. Insert into the chamber outlet and push firmly while rotating clockwise (counter-clockwise unscrews the rod joint).

Work the rods back and forth until you feel resistance give. Run a hosepipe into the chamber to flush — you should see water flowing freely through to the next chamber or out to the highway drain.

If you cannot clear the blockage with rods, or if the blockage is on the highway drain (the section of pipe beyond your boundary), call your water company — Ofwat regulations require them to clear public sewer blockages free of charge.

Common blockages: cooking fat congealed in the drain, wet wipes (never flush these), tree root intrusion in older clay pipes, collapsed or offset pipe joints. Root intrusion requires a drain survey camera (hired from £50/day or by a drain company) and may require pipe lining or excavation.