How-to
New-Build Drains That Already Block: Snagging Problems Developers Don't Mention
Blocked drains in a new build? Mortar, crushed pipes and wrong falls are common faults. A CCTV survey finds them while you're still in warranty.
Published 12 July 2026
Your New Home Has a Blocked Drain. Already.
You moved in six weeks ago. The carpets still smell of fresh paint. The kitchen tap has that satisfying brand-new feel. And the bathroom sink is draining like a tired old man climbing stairs.
Welcome to a very common, very fixable, and very rarely mentioned category of new-build problem: drainage defects that were baked in before you ever turned a key.
This is not your fault. You haven’t blocked anything. The drain arrived broken.
Why New-Build Drains Fail From Day One
A camera survey (that is, a small wheeled robot with a high-definition lens that travels your drain and sends back live footage) is the fastest way to find out what is actually going on inside a new pipe run. What we find in newer builds around Brentford, Isleworth and the wider TW postcode area is, professionally speaking, quite interesting.
Mortar in the Run
During construction, bricklayers and groundworkers are often working in close proximity. Mortar, concrete slurry and building debris get into open pipe ends. If nobody flushes the system before sign-off, that debris sets hard inside the pipe. The drain looks fine from above. Underneath your block-paved drive, there is essentially a partial concrete plug.
Crushed Pipes Under the Drive or Footings
Plastic drainage pipe is tough, but it is not designed to be driven over by a loaded concrete lorry before the trench is backfilled and compacted properly. Crushed or deformed pipe narrows the bore (the internal diameter of the pipe), and anything narrower than it should be will block regularly and enthusiastically.
Mis-Laid Falls
“Falls” means the slope of the pipe, which is what makes gravity do the work. Building regulations specify the correct angle. A pipe laid too flat holds water and lets solids settle. A pipe laid too steep moves water so fast it leaves solids behind. Either way, you get blockages. Either way, the camera shows it immediately as standing water or a visible change in gradient.
Displaced or Poorly Jointed Connections
Push-fit joints in plastic drainage pipe are quick to install, which is exactly why they are popular on busy sites. They are also easy to misalign or leave slightly unseated. A joint that is two millimetres off will let tree roots in within a few years, and will already be trapping debris from day one.
Why This Matters While You Are Still in Warranty
Many new-build homes in England come with a structural warranty and an initial developer defects period. The exact drainage cover, exclusions and reporting deadlines depend on your policy. Check the wording before paying for repairs or assuming a claim will be accepted.
A CCTV drain survey report gives you dated footage and a written description of what the camera found. That turns “the drain keeps blocking” into evidence your developer or warranty provider can assess. It does not guarantee cover, but it is considerably stronger than a description of the symptoms.
Typical cost of a standard residential CCTV drain survey in this area is £150 to £350 depending on the length and complexity of the run. Homebuyer surveys with a full written report start around £250. The cost of any repair depends on its length, depth, access and the surface above it.
Drain relining uses a resin-impregnated sleeve cured inside the existing pipe, avoiding excavation where the defect and pipe condition make lining suitable. Where a pipe is crushed, badly deformed or laid to the wrong fall, excavation may still be necessary. Establish responsibility under the warranty before authorising either repair.
What to Do If You Suspect a Drain Defect
- Note every blockage with a date and a brief description. A simple note on your phone is fine.
- Report it in writing to the developer and to your warranty provider at the same time. Email creates a timestamp.
- Book an independent CCTV survey before agreeing to any developer-arranged inspection. You want your own record, not just theirs.
- Keep the survey report, the footage, and all correspondence together. You will need them if the claim is disputed.
- Do not let anyone “clear” the blockage without first documenting what caused it. Jetting a mortar plug without recording it removes your evidence.
Brentford and the Surrounding TW Area
Brentford has seen significant residential development over recent years, and the surrounding areas, including Isleworth, Hounslow and Kew, are not far behind. We carry out CCTV surveys across the full TW postcode area and produce written reports suitable for warranty and insurance purposes.
A Straight Word Before You Call
If you have raw sewage backing up into your home, that is a health hazard. Do not wait for a warranty process to resolve it. Get it dealt with immediately, document everything, and pursue the developer separately.
For anything else, a blocked or slow drain in a new build is a solvable problem with a clear process behind it. You have rights, you have a warranty, and you have time to use both properly.
If you need a CCTV survey, a drain cleared, or just a straight answer about what you are looking at, call Drainiacs on 07700 137648. We cover the TW area around the clock.