Drain mapping tells you where your drains are. A drain survey tells you what condition they are in. If you are planning building work, you usually need a map. If you have blockages, smells or are buying a house, you usually need a CCTV survey. Often the best answer is both on the same visit. Here is how to decide.
At a Glance
| Drain mapping | CCTV drain survey | |
|---|---|---|
| Answers | Where do the pipes run, how deep, which way do they flow? | Are the pipes cracked, blocked, displaced or full of roots? |
| Main tools | Manhole inspection, sonde and locator, dye testing, measured drawing | CCTV camera, footage and a written report |
| You get | A scaled plan of the drainage layout | A condition report with footage and recommendations |
| Typical reasons | Extensions, build-over agreements, lost manholes, shared drains | Recurring blockages, smells, house purchase, insurance claims |
When You Need Drain Mapping
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Planning an extension or garden room. Your designer needs to know what is underneath. Read our extension drain rules and build-over agreements guides.
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Finding out who is responsible. Ofwat says that since 1 October 2011 your responsibility usually ends at your property boundary, and Thames Water is responsible for sewers shared with neighbours, even under your garden or driveway. A map shows which pipes are shared.
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Lost manholes or no plans at all. See how to find drainage plans for your house.
Find out more about our drain mapping service and how the locating is done in our drain tracing guide.
When You Need a CCTV Drain Survey
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Blockages that keep coming back. A survey finds the cause, whether roots, a sag or a broken joint.
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Buying a house. See do you need a CCTV drain survey before buying?
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Smells, damp patches or subsidence worries.
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Before and after repairs, to check the work.
Our domestic CCTV drain surveys start from £150, and pre-purchase surveys from £180, agreed before we start.
When You Need Both
Major building work, a property with no records, or a drain that needs repairing near a planned extension usually calls for both. Because the camera is already in the pipe, mapping and surveying on the same visit saves time and money.
Frequently Asked Questions
Will a CCTV Survey Show Where My Drains Go?
It shows the route the camera takes and the connections, but not an accurate scaled plan with depths. For that you need mapping.
Does a Mortgage Lender Need a Drain Survey?
Not usually, but a survey can reveal costly defects before you commit, and your solicitor may recommend one for older homes.
How Long Do the Results Take?
We tell you what we found on the day. The written report or drawing follows afterwards.
Not Sure Which You Need?
Call Drain 247 on 0208 387 5591 and tell us what you are planning. We will recommend the right option. We cover Watford, Hertfordshire and North West London; see our areas served.
