Blocked Drains Cleared in North West London

Is it the drain or only the sink?

If several fittings on the ground floor are slow at once, the drain outside is usually the problem. A blocked sink affects one sink. A blocked drain shows up further along the system, so the downstairs toilet gurgles when the bath empties, or water rises in the yard gully when the washing machine pumps out. The quickest test is the inspection chamber, the square cover in the garden, side passage or front path.

Lift it carefully. If the chamber is full of standing water, the blockage is downstream of it. If it is empty while fittings in the house still back up, the blockage is between the house and that chamber. Thames Water gives a useful rule for the other direction. If upstairs fittings are affected but downstairs is working, the blockage is more likely inside the house than in the drain.

Private drain, lateral drain or public sewer: what changed in 2011?

On 1 October 2011, privately owned sewers and lateral drains in England transferred to the water and sewerage companies. Before that date, a shared drain under a row of houses belonged jointly to the owners, and a collapse could mean a bill split between neighbours. The government's announcement on the day set out the split.

Drains shared by two or more properties, and drains serving one property but running outside its boundary, transferred to the sewerage company. A drain serving only one property and lying within its own grounds stayed with the owner.

• Private drain: serves only your property, inside your boundary. Yours to clear
• Lateral drain: serves only your property, outside your boundary. Thames Water's
• Shared drain or sewer: serves two or more properties. Thames Water's

Shared drains in Harrow semis and terraces

In interwar semis and terraces it is common for two or more houses to drain into one pipe before it reaches the road. Once your drain joins a neighbour's, the shared length is a sewer, and clearing it is Thames Water's responsibility, not yours or your neighbour's. This is why we ask whether next door has a problem. If both houses are backing up, the blockage is probably in the shared length or the sewer, and Thames Water should be called first.

Harrow Council's drainage page names Thames Water as the company to contact, on 0800 316 9800. Thames Water says it aims to attend blockages outside the home within 48 hours in normal weather, or 72 hours when exceptionally busy.

What is a gully trap, and why does it keep blocking?

A gully trap is the open drain at ground level where a kitchen or bathroom waste pipe discharges outside, usually under a grid. It holds water in a U-bend to stop drain smells coming up. Because it is open and sits at the lowest point of the waste, it collects whatever goes down the sink. Kitchen gullies block most often. Fat cools and sets in the trap, then traps food scraps and grit.

We scoop the trap out, rod through to the drain, and jet it if the fat has coated the pipe beyond. If your gully overflows only in heavy rain and drains normally in dry weather, suspect the sewer rather than the gully. Harrow Council says water bubbling up from a street grid means the sewer may be backing up, and asks for that to be reported to Thames Water.

Rods or jetting: which does the job need?

Rods suit a single solid blockage, such as wipes or a lump of paper, close to a chamber. Jetting uses a high-pressure water hose that cuts through fat, scale and silt and washes the debris along to the sewer. It suits long runs, kitchen drains coated in grease, and blockages that keep coming back after rodding. We start with the least disruptive method that will work and tell you if we need to change approach.

If a drain blocks again soon after a proper clearance, the cause may be a defect in the pipe: a displaced joint, a root, a dip or a collapse. That needs a camera survey to see, and we do not carry out CCTV drain surveys. We will tell you when one is needed so you can book a drainage specialist.

What causes most blockages, and what can tenants avoid?

Thames Water names fat, oil and food scraps, wet wipes and sanitary items as the main causes of blocked pipes. It says wipes labelled flushable still block pipes. In our experience, a recurring blockage in a rental almost always traces back to one of these.

The fixes are simple and cost nothing. Wipe greasy pans with kitchen roll before washing, and bin the fat once it has cooled. Keep a bin in the bathroom for wipes and sanitary products. Fit a sink strainer in the kitchen.

Landlord or tenant: who pays for a blocked drain?

For most residential tenancies of under seven years, section 11 of the Landlord and Tenant Act 1985 makes the landlord responsible for keeping the structure and exterior in repair, including drains, gutters and external pipes. A blocked or broken drain is normally the landlord's to put right. The exception is a blockage the tenant caused by not using the property in a tenant-like manner. If we pull out a mass of wipes or a set block of cooking fat, we photograph it and say so in our note.

That gives the landlord or agent fair evidence if they want to recharge the cost. If the blockage is root ingress, silt or a defect in the pipe, it is a repair, not tenant misuse. A tenant with a blocked drain should report it to the landlord or agent in writing. If the pipe turns out to be shared or outside the boundary, the landlord does not pay at all, because Thames Water clears it.

What affects the cost of clearing a drain?

Access first. A chamber in an open front garden is quicker than one under decking, a patio or a shed, and buried chambers take time to find. Then the blockage itself: a single plug of wipes near a chamber clears in minutes, while a long kitchen run coated in fat needs the jetter and more time. Before we book, we check whether the pipe is likely to be Thames Water's. If it is, you should not be paying anyone.

Certificates and defined jobs are a fixed price confirmed before we attend; repairs are charged by the hour, with the rate and an estimate confirmed before we attend.

Blocked drains around Harrow and north London

We clear private drains across Harrow, Kenton, Stanmore and Edgware, and in Wealdstone, Harrow Weald, Pinner, Kingsbury, Queensbury, Burnt Oak, Mill Hill and the neighbouring areas. Much of the housing here is interwar semis and terraces with shared runs at the back. So the question of whose pipe it is comes up often.

Thames Water is the sewerage company for Harrow, and for Barnet, which takes in much of Edgware and Mill Hill. Front-garden chambers are often under block paving laid long after the house was built, so tell us if you cannot see a cover.

Plumbing by area: Plumbers in Harrow, Plumbers in Kenton, Plumbers in Stanmore, Plumbers in Edgware, Plumbers in Bushey, Plumbers in Colindale, Plumbers in Hendon, Plumbers in Mill Hill, Plumbers in Northolt, Plumbers in Northwood, Plumbers in Pinner, Plumbers in Ruislip and Plumbers in Wembley.

What we do not do

We do not carry out CCTV drain surveys, drain lining or excavation to repair collapsed pipes. If rodding and jetting show a structural defect, we tell you and recommend a drainage specialist with camera equipment. We do not clear public sewers, lateral drains or shared drains. Those are Thames Water's, and we will tell you to call them rather than charge you. Septic tanks and cesspits are also outside what we do.

Why people trust us

• Repairs tested before we leave, and the area left clean
• A walk-in office on Kenton Lane, not a serviced address
• We diagnose first and tell you what we have found before doing more
• A time slot rather than a morning-or-afternoon window
• Work photographed before and after, and reported
• We tell you when you do not need something we sell

We are building a review profile under this name and would rather show you none than borrow someone else's. Ask us for references from landlords and we will put you in touch.

Official sources

• GOV.UK (Defra): Water customers no longer liable for sewerage repairs, 1 October 2011
• Thames Water: Blockages, who is responsible and what causes them
• Harrow Council: Report a blocked drain
• legislation.gov.uk: Landlord and Tenant Act 1985, section 11

Last reviewed October 2026 by EliteShires Property Services.