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 red 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.