Drain & Water Leak Detection Services
A hidden drain or water leak rarely announces itself the way a burst pipe does. Instead it shows up as a damp patch that will not dry out, a water bill that keeps climbing, or a patch of garden that stays green through a dry spell. Leak detection is about finding that hidden source before it causes structural damage, not just treating the symptom. Drainage & Plumbing Ltd carries out drain and water leak detection across South London, Surrey and the wider South East, using the same CCTV survey and jetting equipment our engineers already use every day on blocked-drain callouts.
Signs You Have a Hidden Drain or Water Leak
Most hidden leaks are found because a customer notices one or two small changes rather than an obvious flood. The most common signs we're called out for are:
- An unexplained rise in your water bill with no change in how much water you're using.
- Damp patches or discolouration on walls, floors or ceilings that keep coming back after decorating.
- A patch of lawn or driveway that stays damp or unusually green when everything around it is dry.
- A hissing or trickling sound near pipework when no taps are running.
- Cracking or subsidence-like movement near a drain run, which can follow prolonged ground saturation from a leaking pipe.
CCTV Drain Leak Survey
We feed a waterproof camera through the drain run to see exactly where a pipe has cracked, opened at a joint, or shifted — the same survey we use for blocked-drain diagnosis, applied to leak-finding.
Pressure & Trace Testing
Where a leak isn't visible on camera, we isolate sections of the system and test them under pressure to narrow down exactly which run is losing water before any ground or floor is disturbed.
Is It Your Pipe or Thames Water's?
One of the first things we establish is whose responsibility the leaking pipe actually is. In most of our service area, Thames Water is the sewerage undertaker. As a general rule, the pipework inside your property boundary — from your internal plumbing out to the boundary of your property — is your responsibility, while the public sewer beyond that boundary is theirs. A leak on a shared drain serving more than one property can sit in a grey area, which is exactly where a CCTV survey earns its keep: it gives you evidence of where the fault actually is before anyone commits to a repair.
Why Hidden Leaks Cost More the Longer They Run
A slow leak rarely stays slow. Water finding its way out of a pipe joint will keep washing away the soil or bedding around it, which is how a small crack turns into a collapsed section of pipe over months. Left long enough, a leaking drain under a driveway or near foundations can contribute to ground movement and subsidence — a far more expensive problem than the original leak. Finding and fixing the leak early, rather than waiting for it to become visible, is almost always the cheaper outcome.
Our Leak Detection Process
1. Initial assessment: we talk through what you've noticed — the bill increase, the damp patch, the sound — to narrow down where to start looking.
2. CCTV or pressure survey: we inspect the suspect run, recording footage so you can see exactly what we find.
3. Clear diagnosis: you get a plain-English explanation of where the leak is, whether it's your responsibility, and what repair options exist.
4. Repair or referral: if it's on your pipework, we can carry out the repair; if it's a Thames Water asset, we tell you so you're not paying for someone else's pipe.
Frequently Asked Questions
We start with non-invasive methods — CCTV camera survey and pressure testing — to narrow down the exact location before any excavation is considered. In most cases this means only a small, targeted dig is needed, if any.
It depends on how straightforward the leak is to locate. We provide a clear price for the survey itself before starting, and a separate fixed quote for any repair once the leak has been found.
Yes, if it runs for long enough. A leaking drain that keeps saturating the ground around it can wash away supporting soil over time, which is why we recommend investigating a suspected leak sooner rather than later.
Yes, we operate 24/7. If you've spotted signs of an active leak, we can usually get an engineer to you the same day.
We'll tell you honestly if that's what our survey shows, and point you to the right process for reporting it to Thames Water rather than charging you for a repair you don't need to pay for.