You are responsible for drains that serve only your property, inside your boundary. Pipes shared with other properties, or beyond your boundary, are usually lateral drains or public sewers belonging to South West Water, who fix problems in them free of charge. Landlords are generally responsible for drainage in rented homes, and most shared pumping stations passed to the water company in 2016. When in doubt, a drainage map or camera survey settles it.
Few homeowners give a moment's thought to the pipes under the lawn until something goes wrong, at which point the first question is not "how do we fix it" but "whose problem is this". The answer decides who pays, and getting it right can save you the entire cost of a repair, because a surprising amount of the pipework near your home does not belong to you at all. This guide sets out the rules as they apply across Cornwall and Devon, where South West Water runs the sewers, and covers the awkward cases: shared drains, rented homes, private pumping stations and unadopted systems.
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Private drains, lateral drains and sewers
Responsibility follows three definitions, and once you know them the rest of the subject mostly falls into place.
A private drain is a pipe that serves a single property and sits within that property's boundary. It belongs to the property owner, who is responsible for clearing and repairing it. A lateral drain is the continuation of that same pipe once it leaves your boundary but before it joins the main sewer, still serving only your property. A sewer is any pipe serving two or more properties, whether it runs under your garden or under the road. Lateral drains and nearly all sewers belong to the water company, which for the whole of this patch, from Plymouth and Saltash out to Liskeard, Tavistock, Totnes and Exeter, means South West Water.
The practical consequence: the point where your pipe crosses your boundary, or the point where it first meets a neighbour's flow, is usually the point where your responsibility ends. Everything downstream of that is the water company's, including blockages, collapses and root damage in it.
The 2011 rule that changed everything
Before October 2011, homeowners could be liable for long runs of shared pipework stretching far beyond their own land, and disputes between neighbours over shared drain repairs were routine. The 2011 transfer of private sewers moved ownership of almost all shared sewers and lateral drains in England and Wales to the water companies automatically. No paperwork was issued to individual homes, which is why so many property deeds still show drainage arrangements that no longer reflect reality, and why plenty of homeowners have paid for repairs that were never theirs to fund.
The rule of thumb since then: serves only you and inside your boundary = yours; shared or beyond the boundary = South West Water's. There are exceptions, mainly systems that never connected to a public sewer, covered further down.
Who is responsible: scenario by scenario
| Scenario | Usually responsible |
|---|---|
| Blocked pipe serving only your house, inside your boundary | You |
| Blocked pipe serving only your house, beyond your boundary (lateral drain) | South West Water |
| Blocked shared run under your garden, also serving next door | South West Water |
| Collapsed public sewer under your drive | South West Water |
| Gully, grate and gully pot within your boundary | You |
| Drains of a rented home | Landlord (unless tenant misuse caused the problem) |
| Shared pumping station, or one outside the property it serves | South West Water (since the 2016 transfer) |
| Septic tank, cesspit or package treatment plant | The property owner(s) it serves |
| Highway gullies and road drains | The highway authority (Cornwall Council, Devon County Council or Plymouth City Council) |
Treat the table as the starting position rather than a verdict. Boundaries on old properties, flying freeholds and pre-1937 shared systems can complicate matters, and where the maps are silent the facts on the ground decide it.
Landlord or tenant?
In a rented home, drainage sits squarely in the landlord's repairing obligations. Section 11 of the Landlord and Tenant Act 1985 makes the landlord responsible for keeping the structure and exterior in repair, including drains, gutters and external pipes, and no tenancy agreement can sign that away. A tenant with a blocked or smelly drain should report it to the landlord or agent in writing, keep a copy, and allow reasonable time for a response.
The one carve out is cause. If the blockage clearly results from what went down the drain during the tenancy, wipes, fat, sanitary products, a toy down the toilet, a landlord can reasonably recharge the clearance. In practice a good engineer can usually say what caused a blockage, which keeps those conversations factual rather than heated. Letting agents across the patch deal with this weekly, and the reports we provide after a clearance state the cause plainly for exactly that reason.
Pumping stations, septic tanks and unadopted drains
Three special cases catch people out, all of them common in Cornwall and Devon.
Private pumping stations
Plenty of modern developments and low lying properties rely on a small sewage pumping station. In October 2016, most of these transferred to the water companies under the same logic as the 2011 sewer transfer: if the station serves more than one property, or sits outside the boundary of the single property it serves, it is normally South West Water's to maintain and power. A pump serving one house within that house's own boundary stays private. If your estate has a pump house nobody admits to owning, this transfer is usually the answer.
Septic tanks and treatment plants
Off mains properties, of which this region has thousands, keep responsibility for the whole system: tank, soakaway and every pipe. There is no water company involvement, and the owner also carries the environmental obligations that come with a private discharge, including the general binding rules on where and how treated effluent can drain.
Unadopted and never connected systems
A shared private system that never connects to a public sewer, for example a group of rural homes draining to a joint treatment plant, did not transfer in 2011. Responsibility stays with the owners jointly, usually as set out in the deeds. Worth checking before you buy, because a share of a failing joint system is a real liability.
How to find out which pipes are yours
Start with paper. Your title deeds and the drainage and water search from your purchase often include a plan, and South West Water can supply public sewer maps for your address. But maps of older systems are frequently incomplete or simply wrong, and the definitive answer comes from tracing the actual pipes: lifting covers, running dye and putting a camera through the runs to map who drains where. That evidence matters twice over: it tells you whether a problem is yours at all, and if it is South West Water's, a camera report showing the defect in their pipework makes the conversation with them short.
If the problem does land on your side of the boundary, the fix is the usual menu: a drain unblocking visit for a blockage, or a targeted drain repair where the pipe itself is damaged. And if your question is specifically about a blockage and who pays for it, our companion guide to blocked drain responsibility walks through that scenario in detail. Either way, we will tell you honestly when a job is South West Water's rather than yours, because charging you for their pipe is not how a local firm keeps its reputation.
Frequently asked questions
Are you responsible for the drains on your property?
You are responsible for the drains that serve only your property and sit within your boundary. Once a pipe serves more than one property, or crosses your boundary on its way to the public sewer, it usually counts as a lateral drain or public sewer and belongs to the water company, which in Cornwall and Devon is South West Water. This split has applied since the 2011 transfer of private sewers.
Is a blocked drain the landlord's or the tenant's responsibility?
The landlord is generally responsible for keeping the structure of the property in repair, including drainage, under section 11 of the Landlord and Tenant Act 1985. However, if a blockage was clearly caused by the tenant's misuse, such as wipes, fat or nappies put down the drain, the landlord may pass the clearance cost on. Tenants should report drain problems in writing and keep a copy.
Will South West Water unblock my drain for free?
If the blockage or fault sits in a public sewer or a lateral drain, which is the section of pipe beyond your property boundary or shared with other properties, South West Water is responsible and will normally clear or repair it at no cost to you. Anything in a private drain serving only your property, inside your boundary, is yours to arrange and pay for.
Who is responsible for a private pumping station?
Most small sewage pumping stations that serve more than one property, or sit outside the boundary of the property they serve, transferred to the water companies in October 2016. If your development has a pumping station that meets those tests, it is normally South West Water's to maintain. A pumping station serving a single property within its own boundary generally remains the owner's responsibility.
How do I find out which drains are mine?
Start with a drainage plan: your property's title deeds or the searches from when you bought may include one, and South West Water can provide sewer maps showing public pipework. Where paperwork is missing or old, a CCTV drain survey traces the actual runs on the ground, maps them, and shows which pipes serve which properties, which settles the question with evidence rather than guesswork.
Not sure whose drain it is? Ask us straight
We work across Plymouth, south east Cornwall and south and west Devon, and we will tell you honestly whether a problem is yours or South West Water's before any money changes hands. If it is yours, you get a fixed price up front.
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