How Much Does It Cost to Unblock a Sewage Drain?

Unblocking a sewage drain costs the same kind of money as any other drain clearance when the pipe is yours, and nothing at all when the blockage is in the public sewer. That split is the single biggest factor in what you pay, so it is worth settling before anyone quotes. After that, the price depends on where the blockage sits, what it is made of, how the engineer has to clear it and whether sewage has come inside. Our own clearance and jetting prices are set by job type and time band on the published rate card; this guide explains what moves the bill up or down so you can check any quote against it.

Do you have to pay to unblock a sewage drain?

Only if the blocked section belongs to you. If the blockage is in a public sewer or in a pipe shared with neighbours beyond your boundary, it is the sewerage company's job, and in most of London that means Thames Water.

Since October 2011, most private sewers and lateral drains that serve more than one property, or that run outside your boundary, have been the water company's responsibility in England. What you still own is the drain that serves only your property, up to the point where it leaves your land or joins a shared pipe. A quick test: lift the inspection chamber nearest the road. If it is full of standing sewage, the blockage is downstream of it, which often points to a shared or public pipe. If it is empty while your toilet backs up, the blockage is on your side. Our guide to who pays for a blocked drain in London walks through the full test, including flats and leasehold buildings.

If several neighbours are backing up at once, ring Thames Water first. Paying a private firm to clear a public sewer is money you should never have spent.

What does a sewage drain clearance usually involve?

Most foul drain blockages are cleared by rodding or high-pressure jetting from the nearest inspection chamber. The engineer works from the chamber upstream or downstream of the blockage, breaks it up and flushes it through to the sewer.

Rodding is the simpler method and suits a soft blockage close to an access point. Jetting uses a water jet at high pressure through a hose, and it is the better tool for wipes, fat and silt that have packed along a length of pipe. A clearance that needs jetting usually costs more than one done with rods, because it needs the jetting unit and more time. If you are comparing quotes, check which method each firm expects to use and whether jetting is included or added once they arrive. Our drain clearance service quotes the method before work starts.

What makes a blocked sewage drain cost more?

Access, the cause of the blockage and the time band move the price most. The word "sewage" on its own should not add anything; a foul drain is the normal kind of household drain.

• No usable access. A buried, painted-over or concreted chamber has to be found and opened first, and that time is chargeable. Where there is no chamber at all, the engineer may have to work from a toilet pan or a gully, which is slower.
• What is in the pipe. Paper clears quickly. Wipes, sanitary products and fat set hard and usually need jetting. Roots growing through a joint need cutting, which is a different job with its own price.
• Depth and length. A blockage a few metres from a shallow chamber is quick. One deep in a long run under an extension takes longer and may need more hose.
• Time of day. Evening and night clearances cost more with almost every firm. If you have a second toilet that still works, waiting for standard hours is often the cheapest decision you can make.
• Repeat blockages. If the same drain has blocked before, a camera check is often needed to find out why. That is a separate line and should be agreed before it happens.

Does sewage inside the house change the bill?

Yes, because clearing the drain and cleaning up after it are two different jobs. A clearance price covers getting the pipe flowing again, not removing sewage from floors, carpets or a basement.

If sewage has come up through a toilet, shower or floor drain, ask separately what the firm charges for extracting standing water, disinfecting hard surfaces and disposing of contaminated material. Some drainage companies do this; others leave it to a specialist cleaning or restoration firm. Either way, it should appear on its own line so you can see it. If you plan to claim on buildings or contents insurance for the damage, take photographs before anything is cleaned and ask for an invoice that separates the clearance from the clean-up. Policies treat the two very differently, and a single combined figure makes the claim harder to support.

When is a CCTV survey worth paying for after a sewage blockage?

When the blockage comes back, when the engineer finds broken pipe or roots, or when water backed up without an obvious cause. A single blockage caused by wipes rarely needs a camera.

A survey shows whether the pipe is cracked, displaced, sagging or collapsed. That decides whether you need a repair or just more care over what goes down the toilet. It is also the evidence an insurer or a water company will ask for if you think the damage is theirs. Our CCTV drain survey is priced as a separate fixed fee with the footage included, so you can take the report to another firm for a repair quote if you want one. What you should avoid is a repair quote given without footage. If someone tells you the pipe has collapsed, ask to see it.

How do you compare quotes for a sewage drain clearance?

Ask each firm the same questions and compare the full price for the likely job, not the headline figure. A low attendance fee with jetting and time added on site can end up more expensive than a higher fixed price.

• Which time band will this be priced in?
• Is the price for rodding only, or does it include jetting if needed?
• What do I pay if the blockage turns out to be in the public sewer?
• Is a camera check included, optional or extra?
• Is clean-up inside the house part of the price or a separate job?

A firm that answers all five before it travels is a firm whose invoice will match its quote. If you are not sure whether the problem is yours at all, describe the symptoms when you get in touch and we will tell you whether to call us or Thames Water.

For how drain unblocking is priced more generally, see our guide to how much drain unblocking costs in London.