TL;DR If the blockage is in a drain that serves only your home, you're responsible for clearing it. If it's in a lateral or shared drain serving multiple properties, Severn Trent Water usually owns the repair, though you may still need to arrange clearance. If it's in the public sewer itself, the water company handles it entirely. Unsure which applies to your property? Get in touch via our online contact form and we can help you work it out.
Private drain, lateral drain or public sewer — what's the difference? The first step in working out who is responsible for a blocked drain outside your house is identifying what type of pipe you're dealing with. A **private drain** serves a single property and runs from the building's internal plumbing to the point where it connects either to a lateral drain or directly to the public sewer. Because it benefits only one household, the homeowner keeps full responsibility for its maintenance and clearance.
A **lateral drain** (sometimes called a private sewer) serves two or more properties before joining the public sewer network. Although it's still physically on private land, it functions as a shared pipe. The **public sewer** is the larger pipe maintained by the water and sewerage company, which collects flow from many laterals and carries it onward to treatment works.
In Birmingham and the wider West Midlands, the public sewer network is operated by Severn Trent Water. Knowing whether a blockage sits in a private drain, a lateral drain, or the public sewer determines who you need to contact — and who is likely to bear the cost. This post focuses specifically on the drain outside your house; for the wider picture of drain responsibility across a property, see our main guide on who is responsible for blocked drains.
The 2011 transfer of private sewers: what changed Before October 2011, homeowners were legally responsible for maintaining not only the drain serving their own property but also any private sewer (lateral drain) serving a group of houses. Regulations introduced that year changed this for most of England and Wales, transferring responsibility for those shared drains to the relevant water and sewerage company.
In the Birmingham area, that means Severn Trent Water took on ownership of the majority of lateral drains serving multiple properties. If a blockage occurs in a drain serving two or more homes, Severn Trent Water is generally responsible for repairing the pipe itself. The transfer did **not** affect drains serving only a single property — those remain private and stay the homeowner's responsibility. It's also worth knowing that even where Severn Trent Water is liable for a structural repair on a transferred lateral, a homeowner may still need to arrange clearance of an immediate blockage to prevent flooding while the repair is organised.
Working out which category applies to your drain A few practical checks help narrow this down. Property deeds or building plans sometimes show the boundary of your private drainage. Severn Trent Water can provide sewer maps showing where the public network begins. If you share a driveway or rear access with neighbours, ask whether they're seeing the same issue — a blockage affecting multiple properties is a strong sign the pipe is lateral or public.
Where there's genuine disagreement, whether with a neighbour or with the water company, a CCTV drain survey provides objective evidence. A camera is fed into the drain to record its internal condition and pinpoint the exact location of the blockage or defect, with findings graded against the WRc MSCC5 standard. Combined with a sewer map, this can show clearly whether the problem sits within your private pipework or in a section that transferred to Severn Trent Water — giving you a solid basis if there's any dispute.
Who to contact first, and when you still need to act If you suspect the blockage is in a lateral drain or the public sewer, Severn Trent Water is your first point of contact — they can advise whether they need to attend or consider it a private matter. Keep a record of your report and any reference number, in case liability is questioned later.
For a confirmed private drain, clearance is down to you. A drainage contractor can attend and use rodding, external drain unblocking, or high-pressure jetting as needed. Even when Severn Trent Water is liable for a structural repair on a transferred lateral, they may still expect you to clear the immediate blockage to stop water backing up into the property while the repair is organised — it's worth handling that clearance promptly and then liaising with the water company on the repair itself.
Getting a clear answer for your property If you're unsure about the ownership of the drain outside your house, the blocked drains service and a CCTV inspection can establish exactly what you're dealing with, wherever you are across Birmingham, Harborne, Erdington, Moseley, Selly Oak, Edgbaston, Kings Heath, Handsworth, Solihull, Sutton Coldfield or West Bromwich. To arrange a visit or talk through a specific situation, use our online contact form — the whole process runs through the form rather than a phone call, so you get a written quote before anything is agreed.
If the property in question is rented rather than owner-occupied, responsibility for a blocked drain works slightly differently between tenant and landlord — see our separate guide on tenant or landlord responsibility for a blocked drain for how that's usually split.
Frequently Asked Questions
**Who is responsible for the drain outside my house?** It depends on the type of drain. If it serves only your property, you're responsible for it. If it's a lateral drain serving more than one property, or part of the public sewer, Severn Trent Water is generally responsible for repairs, following the 2011 transfer of private sewers — though you may still need to arrange clearance of an immediate blockage yourself.
**Who fixes a shared or lateral drain?** Since the 2011 transfer of private sewers, most lateral drains — those serving two or more properties — are owned and repaired by the local water and sewerage company, Severn Trent Water in the Birmingham area. This changed from the pre-2011 position where homeowners were jointly responsible.
**How do I find out if my drain is private or public?** Check your property deeds or building plans if you have them, request sewer maps from Severn Trent Water, and ask neighbours whether they're experiencing the same issue. A CCTV drain survey gives the most reliable answer, since it can pinpoint exactly where a defect sits relative to the boundary between private and public pipework.
**Do I still have to pay if the fault is in Severn Trent Water's section of drain?** You generally won't be liable for the cost of repairing a genuine defect in a transferred lateral drain or the public sewer, but you may still need to arrange or pay for clearing an immediate blockage yourself to stop water backing up, while the structural repair is dealt with separately by the water company.
