Drains and Sewers

Drainage – who is responsible?

Since October 1st 2011 almost all sewers (i.e. pipes used by more than one property) have become the responsibility of Thames Water to maintain. So too have most ‘lateral drains’ - these are individual property drains that lie outside the boundary of the property they come from.  Unless you know that a problem is definitely not in a Thames Water pipe the best thing to do now for almost any drainage problem is to call them, on 0800 316 9800.  If the pipe is theirs they will arrange to unblock or repair it, free of charge. If the pipe is not theirs they will advise you accordingly, and may still offer to deal with it for a fee.

Some pipes are not Thames Water’s responsibility.  You are responsible for the drains that serve just your property, up to the property boundary. You are also responsible for the drain beyond your boundary if it does not ultimately connect with a public sewer. For example if your rainwater drains to a soakaway or to a ditch, or your waste water drains to a cesspit, then you are responsible for the whole drain. And if a pipe that you share with other properties does not discharge to a public sewer then any maintenance needed is the joint responsibility of each owner upstream of the blockage or defect. There are one or two other situations where Thames Water are not responsible but these are limited and Thames Water will tell you if they apply. Where a sewer or lateral drain runs to a private pumping station Thames water will now maintain the pipe as far as the pump. At some time before October 2016 they will also take over the maintenance of the pump. They will let all relevant owners know when that is to happen.

If your drain is blocked inside your boundary, or your drains do not ultimately discharge into a public sewer, you will need to sort out the problem yourself (in cooperation with your neighbours if it is a shared pipe). Some people have insurance policies that cover work to drains, in which case the insurer will give advice about how to go about getting the work done. Otherwise you could agree to pay Thames Water’s charge for a private clearance, or contact a drainage company, or you may be able to do the work yourself if you have access to the right equipment. Sets of drain rods can be bought from DIY stores, hired from tool hire companies or can sometimes be borrowed from friends. If you don’t know where a pipe goes to or whether it is blocked inside or outside the property boundary, or whether it is shared with anyone else, then call Thames Water on 0800 316 9800 to discuss who should deal with it.

In the majority of cases a call to Thames Water will lead to a drainage problem being resolved, often free of charge.  But if the situation is one that Thames Water are unable to do anything about and nobody else deals with the problem then the Council (01923 776611) may be able to help, particularly if it is causing a risk to health. If the problem arises from recent building work then Building Control can advise and if necessary can make the owner comply with the Building Regulations to ensure all new pipes are laid properly. Building Control also keep archived plans showing the proposed drainage of many buildings from when they were first built, and for major alterations since then. If there is a problem with an older drain or to one of the few private sewers that have not transferred to Thames Water then Environmental Health may be able to require the relevant owners to unblock and repair the pipe. Environmental Health can also require owners to remedy discharges that cause pollution, such as if waste water is being discharged into a rainwater system or onto land, and can intervene in privately rented property if a landlord fails to keep a drainage system in satisfactory condition. Environmental Health can also often help with general advice about drainage matters. To call Building Control or Environmental Health call the Council on 01923 776611.

Kerbside gullies and the drainage of roads and pavements are the responsibility of Herts Highways. Please report blocked road gullies and road flooding to them on 0300 123 4047.

To deal with a drainage problem arising from a flooded or polluted watercourse then call the Environment Agency incident line on 0800 807060.

But the best starting point for most drainage problems is a call to Thames Water on 0800 316 9800.


To contact the Council about a drainage query:

Telephone: 01923 776611
Fax: 01923 896119
Address: Three Rivers House, Northway, Rickmansworth, Herts WD3 1RL

External Links:

Thames Water
Telephone: 0800 316 9800

Hertfordshire County Council Highways
Telephone: 0300 123 4047

Environment Agency

To report flooding or pollution affecting watercourses:
Telephone: 0800 807060

for advice about flooding: 

for water pollution:

for advice about septic tanks and small treatment plants:

.Gov – Government advice on dealing with drains and sewers