Blocked Drain in a Welling Semi: You or Thames Water?

Whether you pay for a blocked drain in Welling depends on where the blockage is. Since 1 October 2011, drains shared by two or more properties, and drains serving your house that run outside your boundary, have been the water company’s responsibility, which here means Thames Water. A drain that serves only your house and sits inside your boundary is still yours. If only your home is affected and you do not share a drain, it is most likely yours; if your neighbour is backing up too, or the problem is beyond your boundary, report it to Thames Water before you pay anyone.

Why Welling semis often share a drain

Welling was built almost entirely between the wars: mile after mile of 1930s semis and chalet bungalows from East Wickham to Falconwood. In many of those pairs, each house has its own drain from the toilet, kitchen and bathroom, but the two runs join in a shared pipe or chamber before heading out under the front garden to the public sewer in the road. Some terraces and closes have longer shared runs serving several houses.

So the same blockage could be yours or Thames Water’s depending on whether it is before or after the point where your neighbour’s drain joins.

The 2011 change in plain English

Before October 2011, the owners of a shared drain were jointly responsible for it, and neighbours often argued about who paid. The government then transferred these private sewers to the water companies. In practice:

• Your responsibility: the drain pipes that serve only your property, inside your boundary. That includes the pipes from your toilet, sinks and gullies, up to where they join anyone else’s.
• Thames Water’s responsibility: any drain that serves two or more properties, any drain serving your house that is outside your boundary, and the public sewer.
• Inside the house: the soil stack, the waste pipes and the toilet are always yours.

How to tell where the blockage is

Thames Water’s own guide says a blockage is likely to be yours if only one home is affected, your property does not share a drain, and there is no other flooding nearby. It may be theirs if the problem is outside your boundary or more than one property is affected. It also says that if upstairs is affected but downstairs is fine, the blockage is probably inside your house.

You can narrow it down further with the inspection chambers, the metal or concrete covers in your drive, path or garden.

1. Find the inspection chamber nearest your house, and any others along the run towards the road.
2. Lift the cover carefully with a screwdriver or lifting keys, wearing gloves.
3. Look inside. If it is full of water, the blockage is further downstream.
4. If it is empty or flowing, the blockage is between the house and that chamber.
5. Check the next chamber towards the road and repeat.
6. Ask your neighbour whether their toilet and sinks are draining normally.
7. If the full chamber is on a shared run, or beyond your boundary, report it to Thames Water.
8. If the blockage is on the pipe serving only your house, call a plumber to clear it.

Do not climb into a chamber, and put the cover back securely so nobody falls in.

Signs it is inside the house

• Only one fitting is slow, such as the bath or a basin.
• The upstairs toilet is slow but downstairs drains fine.
• The kitchen sink backs up but the toilet flushes normally.

These are usually a blocked waste pipe, trap or the soil stack, not the underground drain. They are yours to clear.

What usually blocks Welling drains

• Wet wipes, including ones labelled flushable. Thames Water says only pee, poo and toilet paper should go down the toilet.
• Fat, oil and grease from the kitchen sink, setting hard in the pipe.
• Tree roots getting into old clay pipe joints under the front garden.
• Cracked or displaced clay pipes, after ninety years of clay soil shrinking and swelling.
• Silt and leaves in yard gullies.

If a drain blocks again and again, a camera survey will show whether the pipe is damaged. If it is a shared section, Thames Water should repair it.

Reporting to Thames Water

Report a blocked public or shared drain through Thames Water’s website (look for “Report a problem”). Have your address ready, say whether neighbours are affected, and describe which chambers are full. Thames manages the public sewers in this part of Bexley.

While you wait

• Stop using the toilets, sinks, shower and washing machine on that drain.
• Do not keep flushing to “push it through”. It will only back up further.
• If sewage has come into the house, keep children and pets away and wash your hands well.
• Photograph any damage for your insurer.

When to call us

Call us when the blockage is on your side: inside the house, or on the drain serving only your property. We clear blocked drains in Welling and overflowing toilets in Welling. If we find the blockage is in a shared section, we will tell you so you can report it to Thames Water. For a closer look at shared drains under Victorian terraces, see our guide to shared drains in Penge and Anerley. More on the area is on our Welling area page.

Need a plumber now?

Call 07868 281022 and tell us your postcode, which fittings are backing up, whether your neighbour is affected, and what you saw in the inspection chamber. We agree the price with you before any work starts.