Who is responsible for a blocked drain?

The short answer. If the blocked pipe sits inside your boundary and serves only your house, it is yours. If it runs beyond your boundary, it belongs to Severn Trent Water. The same goes for a drain shared with a neighbour, wherever it runs. If water is standing on an adopted road, that gully belongs to Derby City Council.

The three owners, side by side

Whoever owns the pipe pays to clear it. So the only question that matters is where the blockage sits.

What changed on 1 October 2011

Before 2011, a homeowner could own pipework running under three neighbouring gardens. On 1 October 2011 the government transferred most of that pipework to the water companies. In Derby that is Severn Trent Water.

Two kinds of pipe moved across. The first was any sewer shared by more than one property. The second was any lateral drain beyond a property boundary. Anything inside your boundary serving only your house stayed with you.

Severn Trent owns and maintains the public sewers in Derby. Since the 2011 transfer of private sewers, most pipework beyond your boundary became theirs. So did shared drains serving more than one property. The drain that serves only your property, inside the boundary, remains yours.

What a lateral drain is

A lateral drain is the length of pipe carrying waste from your property to the public sewer. It starts at your boundary. It often runs under the pavement or the road.

Severn Trent owns it, even though only your house uses it. That catches people out more than anything else on this page. If a camera shows the blockage past the boundary line, you should not be paying for it.

Shared drains in the older streets

Derby has a lot of Victorian terraces, and terraces were rarely built with one drain each. A single run often collects from four or five houses before it reaches the sewer.

Dense late-Victorian terraces around the Arboretum, most on their original salt-glazed clay drains with rigid joints. Shared runs between neighbours are common, which is why a blockage in one house can show up next door first.

Since 2011 that shared run is a public sewer. So the blockage that fills your gully, but started three doors down, is Severn Trent's to clear.

Roads, gullies and surface water

Derby City Council is the Lead Local Flood Authority for surface water and ordinary watercourses in the city. Highway gullies on adopted roads are theirs; the gully in your yard is not.

Report a blocked roadside gully through the council's blocked gullies form. If water is rising out of a manhole rather than sitting on the surface, the sewer is the likelier cause. Call Severn Trent for that one.

The council is also the Lead Local Flood Authority for surface water in the city. That role covers ordinary watercourses, including Markeaton Brook.

Combined sewers and separate systems

Older parts of Derby drain through combined sewers. One pipe carries foul waste and rainwater together, which is why a downpour can back up a toilet. Newer estates were built with separate foul and surface water pipes.

Which system you are on changes what is allowed to connect where. If you are not sure which serves your street, Severn Trent can tell you. It matters most when you are adding a driveway or an extension, which is covered on our build over drain survey page.

Septic tanks are always yours

If your property is not connected to the main sewer, the tank and its drainage field belong to you. That applies to a septic tank and to a package treatment plant. No water company takes that on.

The Environment Agency's general binding rules set out what you have to do to stay legal. Our septic tank services page explains the practical side.

How to work out whose drain it is

You can usually narrow it down in ten minutes with a torch and a chamber key.

• Lift the inspection chamber nearest the house and look for standing water
• Lift the next chamber towards the road and look again
• Water in the first chamber but not the second points to a blockage inside your boundary
• Water in both usually means the problem sits further down, beyond your boundary
• If chambers along the whole street are full, the public sewer is the likely cause
• If you cannot find a chamber at all, a camera survey will map the run for you

Where the answer is not obvious, a closed-circuit television (CCTV) drain survey settles it. The footage shows the blockage and its distance from the chamber, which is what a water company or an insurer will ask for.

Who to call

Three numbers cover almost every case in Derby.

• Severn Trent Water on 0800 783 4444 for a blocked public sewer, a shared drain or sewer flooding, at any hour
• Derby City Council through the blocked gullies form for standing water on an adopted road
• Drainage Emergency on 01332 215521 for anything inside your boundary, 24 hours, 7 days a week

If we attend and find the blockage is in the public sewer, we will tell you, and we will show you on camera. Sending you to Severn Trent for a free clear costs us a job and saves you a bill. That is the right way round.

This page explains how responsibility is normally split in Derby. It is general information, not legal advice, and unusual arrangements do exist. Severn Trent Water can confirm what they own at your address.