Blocked Drain in London? Who's Responsible and What to Do

When a drain blocks, the first question most people ask is “whose problem is this?” The answer depends on where the blockage is — and in London, that is often not where you'd expect.

The basic rule

Pipes that serve only your property and sit inside your boundary are generally your responsibility. That includes sink and bath wastes, toilet connections, the soil stack and the drain running under your garden until it meets a shared pipe or crosses your boundary.

Since October 2011, most shared drains (serving more than one property) and lateral drains (the section outside your boundary that connects to the public sewer) have been owned and maintained by the water company. Across most of London that's Thames Water.

What this means for terraces and flats

In a Victorian terrace, several houses often share one drain running along the back gardens. If the blockage is in that shared section, the water company should clear it. In a block of flats, the internal soil stack and communal drains are usually the freeholder's or managing agent's responsibility, while the waste pipes inside your flat are yours.

Renting? Tell your landlord first

Tenants are normally responsible only for blockages they cause — for example by flushing wipes or pouring fat down the sink. Structural drain problems are the landlord's to fix. Report problems promptly in writing.

How to tell where the blockage is

• Only one sink or toilet is slow: the blockage is almost certainly in your own waste pipe.
• Everything in the house is backing up: the main drain is blocked — lift your inspection cover (manhole). If it's full, the blockage is downstream.
• Your manhole is empty but the house is backing up: the blockage is between the house and the chamber — your responsibility.
• Neighbours have the same problem: it's likely in a shared section — call Thames Water.

Prevention

Bin wipes (even “flushable” ones), cotton buds and sanitary products. Let fat cool and put it in the bin. Fit hair catchers in showers. And if you have recurring blockages, a CCTV drain survey can find damage before it becomes a collapse.

Not sure where your blockage is? Call LPS — we'll find it, clear it if it's yours, and tell you straight if it isn't.