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03 July 2015

What is the difference between a drain and sewer and who is responsible for them?


What is the difference between a drain and sewer and who is responsible for them?


Drain - A drain is a pipe taking foul or surface water flows from one property.

Sewer - A sewer is a pipe taking foul or surface water flows from two or more properties.

Sewage - Is the effluent or water that passes through the sewer or drain.

Sewerage - Is the system or network of pipes that form the sewer connections from head to discharge at the treatment works or other final outfall.

Public or Main Sewer - A public or main sewer is part of the network of publicly owned foul or surface water drainage systems. These systems are managed by the sewerage undertaker and accept the flows from the smaller private drains.

Surcharge - When flows cannot be contained within the piped system then the excess flows will escape (surcharge) through the nearest low or weakest point upstream of the restriction, usually an inspection chamber.

Responsibilities for drains and sewers.
As and from the 1st October 2011 responsibility for maintaining all private sewers and lateral drains located in the Thames Water Utilities Ltd sewerage area (the whole of Surrey Heath is within this area) were transferred to them. Accordingly any problems encountered with your lateral drains beyond the curtilage of your home and sewers should in the first instance be reported to Thames by telephoning 08459 200 800. (This is the same even though you may pay your water bills to a different company).

Thames Water should dispatch a drainage engineer to inspect the system and ascertain the cause of the problem. If the blockage or defect is located in the public sewer system they will arrange for its clearance or repair without further cost to the enquirer. If however they discover that the problem is not connected with their system and it is either part of a private drain or sewer system they will refer it back to the owners. They may offer to clear or repair the defects but please be aware they can then charge for this work.
How does the sewer/sewerage system for my property work?

If your property is of individual design (e.g. not of similar look to your neighbours) then it is likely to have been constructed with a single drainage connection (one for foul/waste water and possibly one for surface water as well) into the main public sewers. In these circumstances there will probably be a private drain from the house to the property boundary (curtilage), which is the private responsibility of the owner or occupier of the property but from there onwards it is the responsibility of Thames Water.

If your property is of similar design (e.g. of similar look to your neighbours and likely to have been developed at the same time) then the property is likely to have been connected to several other properties. In these circumstances each house will have a lateral drain emerging from it and each will be the responsibility of the owner or occupier of that particular house. From the point where two or more drains join together it may be the responsibility of Thames Water Opens in a new window (i.e. Where the private sewer outfalls into a watercourse).

Thames Water website contains definitions and pictures of what should be a public sewer and what might still be a private lateral drain. If you are in any doubt as to whether the problem is located in the public system or it is one for private action to resolve you must contact Thames Water who can provide you with a definitive answer.

Thames Water Utilities Ltd. Opens in a new windowWhere there is dispute you can bring this to the attention of the Local Authority who may investigate the matter for you. Ultimately however the responsibility will be either a private one or one falling to Thames Water Utilities Ltd. If you are in any way dis-satisfied with the service you have received from them you will have to make a formal complaint firstly through Thames Water's complaints procedures and then if still dis-satisfied through the Water Industry Regulator OFWAT.

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