Dealing with drain or sewer blockages
If you have a blockage, try to find out if it is in your drain or in a drain or sewer outside your property boundary.
Talk to your neighbours. If they are affected too then the problem is likely to be in a sewer. Thames Water handles blockages in the sewer. Report the blockage on the Thames Water website.
If you’re the only one affected, the problem is probably with your own plumbing. Thames Water is not responsible for blockages within your property boundary. Call a plumber or try to resolve the problem yourself. Thames Water has a list of WaterSafe approved plumbers.