How can I tell my drain is blocked?

The signs are usually easy to spot. Water drains slowly from more than one sink, bath or shower. A toilet gurgles when another appliance is emptied. A gully outside the back door fills and does not clear. A drain cover in the garden or driveway is full of water, or there is a lasting smell near it.

A single slow basin is often a blocked trap or waste pipe. When several fixtures misbehave at once, the cause is more likely to lie in the main drain that carries everything away from the house.

Which pipe is mine to deal with?

The answer depends on where the blockage sits. A drain that serves only your property, running from the house to your boundary, is normally your responsibility.

Since October 2011, drains that serve more than one property, and the lateral drains that run from the boundary to the public sewer, have generally been the responsibility of the water company, as the government announced when the change took effect. In this area the sewerage company is usually Thames Water. Your tap water, and often the bill, may come from Affinity Water, which does not run the sewers. Your bill shows who handles your sewerage.

If you think the blockage is on a shared pipe or beyond your boundary, report it to your sewerage company first. Thames Water explains which pipes are yours and which are theirs. An engineer who attends can often tell you which side of the line the problem is on.

What can I try before I enquire?

Run the taps in other rooms to see how widespread the problem is.
Look in the nearest gully for leaves, grease or other debris you can clear while wearing gloves.
Use a plunger on a blocked sink or toilet.
Avoid pouring bleach or strong drain chemicals into a drain that is already backing up. They rarely shift a serious blockage and can be hazardous to whoever works on it next.

Leave heavy inspection chamber covers alone unless you know how to lift them safely.

How do engineers clear a blocked drain?

Most engineers start by finding where the blockage is, then choose a method to suit. Drain rods are pushed along the pipe to break up or pull out a plug of waste. High pressure water jetting uses a pressurised hose to cut through grease, scale or silt and flush it away. A camera is often run through the pipe afterwards to check the drain is clear and to look for the reason it blocked.

What should never go down a drain?

Most repeat blockages begin with something that should never have been poured or flushed.

Fats, oil and grease. They cool and set inside pipes, trapping other waste.
Wipes, even those labelled as flushable. They do not break down like toilet paper.
Nappies, cotton buds, sanitary products and dental floss.
Food scraps, coffee grounds and rice.
Paint, cement and plaster.

Only urine, faeces and toilet paper belong in a toilet.

Is sewage backing up a health risk?

Yes. Sewage can carry bacteria and viruses. Keep children and pets away from any area it has reached, wear waterproof gloves if you have to touch anything, and wash your hands thoroughly afterwards. Do not use affected toilets or sinks, because every flush adds more to the problem.

Wash hard surfaces with hot water and disinfectant, and keep food and food-preparation areas clear of it. Soft furnishings and carpets soaked by sewage often cannot be cleaned safely, so ask for advice. Some home insurance policies include cover for drains, so check yours.

What if it keeps blocking?

A drain that blocks again and again usually has a reason. Tree roots may be growing into a joint, a section of pipe may have sagged or cracked, or the pipe may be too narrow or too flat for the waste it carries. Clearing the blockage treats the symptom. A camera survey of the drain can show the cause, and a repair may then be needed.

Does this apply to businesses?

Yes. Cafes, takeaways, shops and workplaces face the same problems, usually with more grease and heavier use. If you run a food business, say so in your enquiry, and mention any grease trap you have.

What should I put in my enquiry?

your postcode and whether the property is a house, flat or business premises
which sinks, toilets or gullies are affected
when you first noticed the problem
whether you share a drain with neighbours
whether anything unusual went down the drain beforehand

What happens after I send it?

Enquiring is free and you are not committed to anything. Any work and its cost are agreed between you and the engineer. This is not an emergency call-out service.

Who you will hear from

We pass your enquiry to one local drainage engineer, if one covers your postcode. It is never sent to a list of companies. If nobody covers your postcode, we will tell you and will not pass your details on.