Sewer responsibilities

You might think that as we take away your used water that all the drains and sewer are our responsibility. But actually you or your landlord are responsible for some pipes.

What do you own?

The purple pipes in the picture below. Pipes that only collect wastewater from your property, and which lie inside your home or within the boundary of your property are your responsibility.

What do we own?

The orange pipes in the picture below. Pipes that drain your own home, but lie outside your boundary and pipes serving both you and your neighbours are probably our responsibility.

What does the council own?

Councils are responsible for all blockages on properties they manage, highway drains and gulleys.

What to do if you have a blockage on your own pipes?

If none of your neighbours have any problems, it is likely the blockage is on your private pipes. If you have a problem with any of your private pipes contact a reputable drainage contractor, who will be able to help you. The costs of fixing any faults on this pipework will be yours or your home insurers.

What to do if you think you have a blockage on Welsh Water pipes?

If you suspect there is a blockage on a Welsh Water sewer, then call us on 0800 085 3968 and we will investigate the problem.

Not sure where the blockage is?

Sometimes it can be hard to determine where the blockage is, If you are unsure who is responsible for the Wastewater pipe, please contact us on 0800 085 3968 and we can help determine the ownership.

To continually improve the accuracy of our drainage records we’d welcome copies of any plans you have which show the drainage around your home.

Please email a digital copy (preferably scanned or photographed in .pdf or .jpg format) to us at

Alternatively, send a paper copy by post to:

GIS Bureau
Dwr Cymru Welsh Water
Fortran Road
St Mellons

* Remember to tell us which address the plan relates to.

You don’t need to provide any letter or additional detail with your plan.

Land drains and watercourses

Responsibility for drainage in our urban communities is complex and shared between ourselves, local authorities, Natural Resources Wales and local land or property owners. Occasionally, this means that we add a pipeline to our maps that isn’t our responsibility.

Land drains and watercourses carry ground water and surface water away from our natural landscapes. Many of these drains and streams will have been piped under our towns and cities when development took place.

In most cases these drainage systems will be the responsibility of the land owner whose property they pass through, or who’s land they adjoin. These responsibilities are known as Riparian Rights and you can find further information about them on the Natural Resources Wales website.

Maps of the sewers that we maintain have been assembled over generations. In some cases we find that land drains, underground streams (culverted watercourses) and highway drains have been wrongly added to our maps. These additions were often made with good intentions, but they can cause confusion about who’s responsible for their maintenance.

To help confirm ownership of these pipes we’ll carry out a detailed investigation whenever our staff, or those of another drainage agency, report a potential mapping error to us. To ensure this is carried out fairly we aim to follow a national procedure in these cases, a copy of which can be found on the Water UK website.

Local authorities and Natural Resources Wales can report any errors they find by downloading and completing the NOF 029 - Application for Asset Status Change – Proforma. Investigations can take several months to complete, so it’s important that all available evidence is submitted with any application.

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NOF 029 - Application for Asset Status Change - Proforma

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