Blocked outside drain or inspection chamber
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A blocked external drain is one of the most common—and unpleasant—problems UK homeowners face, especially in older properties with clay pipework or those surrounded by tree roots. When your inspection chamber (the manhole cover in your garden) fills up with sewage instead of draining away naturally, it's a sign that something downstream is preventing water from flowing into the public sewer. This usually happens gradually, though heavy rainfall, fat buildup, or structural damage can trigger it suddenly. The good news is that most blockages can be cleared quickly and affordably without digging up your garden. This guide walks through how to identify whether the problem is yours to fix or the water company's responsibility, and what your realistic options are for getting it sorted. If you're uncomfortable dealing with sewage or the blockage persists after initial clearing, it's absolutely the right call to contact a professional drainage contractor.
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Most likely cause & what to check
Locate your inspection chamber — the plastic or concrete square cover in the garden or driveway. Lift the lid carefully using a screwdriver to lever it up.
Check if the chamber is full of water — if it is, the blockage is downstream of this point (towards the sewer). If it's empty, the blockage is upstream (between the chamber and the house).
Using drain rods (available to hire from tool hire shops for around £15): screw rods together one section at a time and push into the drain in the direction of the blockage. Use a clockwise twisting motion to help push through.
When you feel resistance, keep twisting and pushing. You will often feel a sudden release when the blockage clears — water will rush through.
Flush the drain with a hose pipe for several minutes to clear any remaining debris.
If you cannot clear the blockage with rods, or if there is a persistent problem, call a drainage company to jet-wash the drain. This is far more effective for grease or root ingress.
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Frequently asked questions
Who is responsible for blocked drains — me or the water company?
You are responsible for drains within your property boundary. Once the drain joins the public sewer (usually at the boundary), it becomes the water company's responsibility.
How much does a drainage company charge to clear a blocked drain?
Typically £80–£200 for a high-pressure water jet clean, depending on the severity and location.