Drains are the part of a house nobody sees, and that’s exactly why they catch buyers out. Repairs can be disruptive and expensive, and once you exchange contracts, any problem is yours. A drainage survey before you commit is one of the most useful extra checks you can arrange.
What a surveyor can and can’t see
During our inspection, we lift accessible inspection chamber covers where it’s safe to do so, run the taps and look for blockages, standing water and signs of past problems. What no surveyor can see is the inside of the pipes running underground. That’s where a specialist CCTV drainage survey comes in.
Common drain problems in older homes
Cracked or displaced pipes. Older clay pipes crack and their joints shift over time, especially under driveways.
Roots. Tree and shrub roots find their way into joints, block the pipe and break it apart.
Collapsed sections, which can cause repeated blockages and smells.
Pitch fibre pipes. Used in some mid-20th-century homes, these can soften, blister and deform with age.
Leaks under the house. Escaping water can wash away the soil under the foundations and is a known cause of subsidence.
Extensions built over drains without the right protection or consent.
Why get a drainage survey before you exchange
A drainage specialist runs a camera through the pipes and gives you a report, usually with footage, showing their condition and any defects. Doing this after your offer is accepted but before you exchange gives you time to get repair quotes, renegotiate, or ask the seller to put things right.
We especially recommend one if:
The house is older, or the drains are likely to be original.
There are trees or large shrubs near the drain runs.
There are signs of movement or cracking in the house.
The house has been extended over or near the drains.
Drains are slow, or there are smells or recurring blockages.
The property has a septic tank or private treatment plant.
Shared drains and public sewers
In England and Wales, most shared sewers and lateral drains outside your boundary became the responsibility of the water companies in 2011. Drains that serve only your property, within its boundary, are still yours to maintain. Your solicitor’s drainage and water search shows how the property is connected and whether a public sewer runs through the garden. Building over or near a public sewer may have needed the water company’s consent.
Septic tanks and treatment plants
If the house isn’t on mains drainage, ask the seller about the system’s age, service records and where it discharges. In England, rules introduced in 2020 mean a septic tank that discharges directly into a ditch, stream or other watercourse must be replaced or upgraded, and the seller must tell the buyer about the system in writing. Have a specialist inspect it before you exchange, and ask your solicitor to check it complies.
Keeping drains healthy once you move in
Don’t pour fats and oils down the sink, or flush wipes.
Keep gullies and drain grids clear of leaves and silt.
Know where your inspection chambers are.
Act quickly on slow drains or smells. Small problems are cheaper to fix.
Check what your buildings insurance covers for drains.
Questions we’re often asked
Does a Level 2 or Level 3 survey include a drainage survey?
No. Both include a visual inspection of what is accessible, but not a camera survey of the pipes. If we think one is needed, we’ll tell you clearly in your report and on our call.
When should I book it?
Once your offer is accepted and before you exchange contracts, ideally alongside your survey.
Who pays for it?
Usually the buyer. If it finds problems, the report gives you evidence to renegotiate or ask the seller to repair.
How we help
We only book one survey a day, so we have time to look properly, including lifting accessible covers and checking how the drains are working. If we recommend a drainage survey, our helpful guides with your report explain what to arrange, what to ask your solicitor and what to raise with the seller. We’re always a phone call away until you have the keys.
Buying a home? Use the Get My Quote button above, or call us on 01451 828107 (Cotswolds) or 01256 578063 (Hampshire).
Max Daniel AssocRICS, Director, MJD Residential Surveying