Who Is Responsible for a Blocked Drain? You, Your Landlord or Thames Water

Who is responsible for a blocked drain?

You are responsible for a drain that serves only your property and sits inside your property boundary. Once the pipe leaves your boundary, or joins a pipe that also serves a neighbour, it is generally the water company's responsibility. In most of London, that means Thames Water. So the answer depends on where the blockage is, not on where you first notice it.

What changed in 2011?

Before October 2011, many shared pipes running under back gardens and driveways were privately owned, and neighbours often had to split the bill when one blocked. On 1 October 2011, the law changed in England and Wales. Most private sewers and lateral drains that connected to the public sewer were transferred to the water companies. Since then, water companies have looked after far more of the underground network, including many pipes on private land. If you were told years ago that a shared drain was your joint problem, that advice may now be out of date.

Drain, lateral drain or sewer: what is the difference?

A drain is a pipe that carries waste from one property only, within that property's boundary. That is yours. A lateral drain is the part of that same pipe which runs outside your boundary, often under the pavement or the road, before it joins the sewer. Since 2011 that section is generally the water company's. A sewer is a pipe that carries waste from two or more properties. Shared sewers, including those running through private gardens, are generally the water company's too. There are some exceptions, such as pipes that run to a private septic tank, and some sewers on newer estates that have not yet been formally adopted.

How to tell if the blockage is in your drain or a shared one

Start by looking at which fixtures are affected. If only one sink or toilet is slow, the blockage is almost certainly in that fixture or its own waste pipe inside the house, and that is yours. If everything in the house is backing up, the blockage is in the main drain. Then lift your inspection cover, the manhole cover in your garden or driveway. If the chamber is full of water and waste, the blockage is further down the line. If it is empty and clear, the blockage is between the house and that chamber. If your neighbour's chamber is also full, or the flooded chamber is one you share, it is very likely in a shared sewer. Water companies can usually tell you from their sewer maps where your private drain ends. Many London terraces have no manhole in the front garden, because the drain runs out under the pavement or out the back into a shared run behind the houses. If you cannot find a cover, look along the front and back of the house and in the gardens either side, as a shared chamber may sit on a neighbour's land. Covers can be heavy and rusted in place. Use a proper lifting key or a pair of old screwdrivers under the lip, lift with your legs rather than your back, and never leave an open chamber unattended, especially with children or pets about. If the cover will not budge, do not force it.

Who pays if you rent: landlord or tenant?

In England, landlords must keep the drains and the pipes for sanitation in repair under their repairing duties in the tenancy. So if the drain is private and blocked through normal use, or because of a fault such as a cracked or sunken pipe, it is the landlord's job to fix and pay. The exception is a blockage the tenant caused, such as wipes flushed down the toilet or cooking fat poured down the sink. Then the landlord may pass the cost on. Either way, tell your landlord or letting agent in writing as soon as you notice a problem.

What about flats: freeholder or leaseholder?

In a block of flats, the pipes inside the building, such as the soil stacks that carry waste down from each flat, are usually the responsibility of the freeholder or the management company, and paid for through the service charge. Your own waste pipes up to where they join that shared stack are usually yours. Once the shared pipe leaves the building and joins the network, it is generally the water company's. Leases differ, so check yours for the section on repairs and "service media", which is lease wording for pipes and cables.

Who to call in London

If you think the blockage is in a shared sewer or a lateral drain, report it to the sewerage company. For almost all of London that is Thames Water, even in areas where a different company supplies your drinking water. They do not charge you for clearing a public sewer. If the blockage is in your own drain, you will need to clear it yourself or pay someone. Our guides on how to unblock a drain and on a blocked outside drain show what you can safely try first.

When to call a plumber

If the blockage is clearly in your own drain and rods or a plunger have not shifted it, it needs clearing with proper equipment. We clear a blocked outside drain for a fixed £140 to £240, agreed in writing before we start, with no call-out fee and no extra charge at night or at weekends. If we find the blockage is in a shared sewer, we will tell you, so you can report it to Thames Water rather than pay for work that is theirs to do.

Who Is Responsible for a Blocked Drain? You, Your Landlord or Thames Water, your questions

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