Blocked inspection chamber or manhole — how to clear it
Check the steps below first — if you're not confident, get it fixed safely today.
Post a job — we'll find you an engineer →⚠️ Never enter a confined manhole or inspection chamber. Sewage spaces can contain hydrogen sulphide and other toxic or explosive gases. Use drain rods from ground level only.
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Most likely cause & what to check
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.
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Frequently asked questions
How do I know if a drain blockage is my responsibility or the water company's?
Generally, drains within your property boundary that only serve your property are your responsibility. The sewer main in the public highway is the water company's responsibility. If your inspection chamber is full but the chamber at the boundary is empty and draining, the blockage is in your section of pipe. If both are full, the blockage is downstream in the public sewer.
Can I hire drain rods myself?
Yes — drain rods can be hired from most tool hire shops for £15–£30 per day. They come in 1-metre sections that screw together. Use the rubber plunger or corkscrew attachment and always rotate clockwise — counter-clockwise unscrews the sections and you may lose a rod in the drain, which is a much bigger problem than the original blockage.
When should I call a drain company rather than tackling it myself?
Call a professional drain company if: you cannot clear the blockage with rods, the blockage keeps recurring, you suspect tree root intrusion, there is an unpleasant smell even after clearing, or the drain is over 3 metres deep. A CCTV drain survey (£100–£300) identifies the root cause of persistent blockages.