New Build Drainage Problems Tewkesbury | Spot Them Early

You've moved into a new house on one of the Ashchurch or Northway developments. The kitchen is clean, the carpets are fresh, the boiler hasn't thrown a single fault code. Then, six months in, the downstairs toilet gurgles every time someone runs the bath upstairs. Or there's a faint smell near the utility room that wasn't there before. Or you spot a soft patch of lawn directly above where the sewer run should be.

These aren't bad luck. They're patterns. New-build drainage on the bigger Tewkesbury estates, Ashchurch, Northway, Wheatpieces, Priors Park, produces a surprisingly consistent set of defects. I see them regularly enough that I can almost predict what the camera's going to find before I push it down the inspection chamber.

The reason matters. If you understand what tends to go wrong and why, you can catch it during your snagging window rather than two years after the developer has moved on to the next phase.

Why New Builds Aren't the Clean Slate They Look Like

There's a common assumption that new pipes equal no problems. Old clay pipes under a Victorian terrace in Tredington? Sure, those crack, root-intrude, and belly. But brand-new plastic drainage in a 2022 house on a Gloucester Road plot? What could go wrong?

Quite a bit, it turns out.

New-build drainage is installed by groundworks subcontractors working fast on tight programmes. Pipes get laid, inspected to a minimum standard, and then the site moves on. Backfilling happens. Concrete gets poured. Houses go up. The drainage is buried and essentially forgotten. If the CCTV survey before sign-off was done at all, it was often done on behalf of the developer rather than the buyer. That's not an accusation of bad faith. It's just how the incentives work.

The result is that defects get built in, literally, and they don't show symptoms until the system is under load. Which means after you move in.

The Most Common Defects We Find

Construction Debris in the Pipe

This is the one I'd stake money on finding on any new-build CCTV survey we do around Ashchurch. Mortar, concrete splatter, broken roof tile fragments, even whole bricks have ended up inside drainage pipework. During construction, drainage access points are convenient places to tip waste or let slurry run. Inspection chambers get used as skips. Pipes that haven't been capped get filled with whatever falls or gets kicked in.

Small debris washes through. Larger pieces settle at the first change in gradient and stay there. Over time they catch wet wipes, grease, and hair, and what was a half-blocked pipe becomes fully blocked. The call I get is always described as a recurring blockage. It is, technically. But it's a blockage caused by a structural obstacle, not by the habits of the occupants.

High-pressure water jetting will clear it, but if the debris is heavy enough it can damage the pipe wall too, so the camera goes in first.

Falls That Aren't Quite Right

Drainage pipes need a consistent fall to self-cleanse. Too shallow and solids settle. Too steep and the liquid outruns the solids, leaving them stranded. The recommended gradient for a 100mm drain is around 1:40 to 1:80 (roughly 1.25 to 2.5cm drop per metre of run). Getting this consistently right across a 20-metre run through ground that's still settling is harder than it sounds.

On sites like Ashchurch where ground conditions are mixed, and where significant import fill has been used to build up plot levels, post-construction settlement can shift pipe gradients noticeably within the first year or two. A pipe that was laid at the right fall can end up with a belly, a low spot where water pools rather than flows. Solids accumulate at the belly, the system starts to smell, and eventually it blocks.

You can't see this from above ground. The camera shows it immediately.

Displaced or Poorly Made Joints

PVC push-fit drainage joints are quick to install and reliable when done right. Done under time pressure on a muddy site in November, they're less reliable. A joint that isn't fully seated can allow soil and groundwater ingress, can develop a lip that catches debris, or can pull apart slightly under ground movement.

On the CCTV footage this shows as a visible step or gap at the joint. If it's letting groundwater in, you'll see a wet ring or active seepage. If root intrusion is already happening (it starts faster than most people expect, even in new ground), you'll see fine root tendrils at the joint within two or three years.

Inspection Chamber Issues

New-build inspection chambers are often a mix of precast concrete base units and plastic riser rings topped with a cover. The transitions between materials, and between the chamber and the incoming and outgoing pipes, are common failure points. Gaps at the benching, cracks in mortar around the pipe entry, covers that aren't set to the right level and take vehicle loadings they weren't designed for.

A cracked or poorly sealed chamber isn't just a structural problem. It's an environmental one. Sewage leaking into ground on a new estate affects neighbouring properties. Groundwater infiltrating the chamber adds unnecessary flow to the sewer system.

The Shared Private Sewer Problem

This is the one that surprises most new-build buyers the most, and it's worth explaining carefully.

On many new estates, multiple houses connect to a shared private sewer before the flow reaches an adoptable public sewer or an adoption point maintained by Severn Trent. The section of pipe that serves more than one property but hasn't yet been adopted is legally shared between the owners whose properties drain through it.

What that means in practice: if the shared section blocks or collapses, no single resident owns it outright, and Severn Trent won't attend because it isn't on their adopted network yet. The residents served by it are jointly responsible for repair.

On a brand-new estate this sounds abstract. After five years, when the estate has moved from 'new-build' to 'just houses', and neighbours have changed, and no one has a copy of the drainage layout drawing, it becomes very concrete. Especially if the block is in the shared section and the first three residents it affects all assume it's someone else's pipe.

The adoption process takes time. Developers submit drainage to Severn Trent for adoption under a Section 104 agreement, but the process can take years after the last house is built. Until adoption is confirmed, the sewers are the residents' responsibility.

If you're buying on a new Ashchurch phase, ask your solicitor directly: what is the current adoption status of the drainage serving this plot, and is there a Section 104 agreement in place? Don't assume it's sorted.

The Developer Sign-Off Gap

Most new-build warranties (NHBC Buildmark is the most common) cover drainage defects, but the process for making a claim isn't always obvious. In the first two years, defects are referred back to the developer to fix. After year two and up to year ten, NHBC cover kicks in for major structural defects, but the definition of 'major structural' doesn't always stretch to a partially blocked drain or a belly in a pipe.

The gap that catches people out is this: they notice a symptom in year one, report it to the developer's customer care team, are told it's a 'normal settlement' or that they'll send someone to look at it, and nothing happens. The two-year developer liability period expires. Now it's a homeowner problem.

The way to protect yourself is a CCTV drain survey done before you exchange (if you can) or within the first few months of moving in. If the survey finds debris, a displaced joint, or an incorrect fall, you have documented evidence to support a snagging claim. Without the survey, you're relying on the developer accepting your verbal description of a smell or a slow drain. That rarely goes well.

What a CCTV Survey Actually Finds: A Job on Ashchurch Road

Last year we got a call from a couple who'd bought on one of the newer phases off Ashchurch Road. They'd been in just over eighteen months. The complaint was a drain in the rear garden that was backing up every few weeks. They'd had it cleared twice by another company, both times with a high-pressure jetter. It cleared, came back within six weeks.

We pushed the camera down the inspection chamber at the rear of the garden. Within three metres, there was a significant mortar deposit sitting on the invert of a 110mm pipe, narrowing the bore by about a third. Not enough to block it outright, but enough to catch anything solid that came through. Behind the mortar deposit the camera picked up a joint that was slightly displaced, creating a small step into the pipe. Twelve metres further along, where the run turned toward the shared sewer, there was a clear belly, a dip of about 30mm, where the pipe had settled unevenly.

The mortar was physical debris from construction. The displaced joint was a poor installation. The belly was post-construction ground settlement. Three separate issues, all invisible from the surface, all contributing to the same recurring symptom.

We cleared the mortar with jetting, relined the section at the displaced joint using a short-form CIPP liner (cured-in-place, no dig), and documented the belly for the homeowners to take back to the developer with the footage. The belly wasn't severe enough to cause collapse, but it was enough to be a legitimate snagging item.

They went back to the developer with the CCTV report. Got a dispute, then a reinspection by the developer's own contractor, who confirmed the belly. It was rectified under the developer's two-year liability, just before the window closed.

Without the survey, they'd have kept paying for jetting every six weeks indefinitely.

Comparing Your Options

The honest read: pre-exchange is the cleanest option because any defects found are the developer's to resolve before you complete. Year-one surveys are the next best thing. Waiting until you have a problem means paying for repairs that should have been warranty items.

What to Do If You're on a New Tewkesbury Estate Right Now

A few practical things:

• Get hold of the drainage layout drawing. Your solicitor should have received this at conveyancing. If not, ask the developer's sales office. You want to know where your private drains run, where the shared section starts, and what the adoption status is.
• Check your inspection chambers. Lift the covers if you can do it safely. Look for signs of cracking, poorly finished benching, or water staining that suggests infiltration. Take photos and date them.
• Don't keep clearing the same blockage. One blockage might be bad luck. Two in the same place within twelve months is a pattern worth investigating. Get the camera down before the next jetting visit.
• Act within the two-year window. Developer liability for defects runs for two years from legal completion in most standard warranties. Symptoms that appear in month twenty need to be reported now, not after month twenty-four.
• If there's any smell, slow drainage, or soft ground near the sewer line, treat it as a snagging item and document it. Timestamped photos and written records of every conversation with the developer's customer care team.

The Lesson Worth Taking Away

New doesn't mean problem-free. The drainage on Ashchurch and the surrounding GL20 estates was installed by people working fast in difficult ground conditions, and it was buried before most of the problems had a chance to show themselves. That's not a scandal. It's just construction.

But the sign-off gap is real, the shared sewer confusion is real, and the two-year window is unforgiving. A camera survey is a few hundred pounds. Digging up a collapsed shared sewer three years after your developer has moved on is not.

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If you're on a newer development in or around Ashchurch, Northway, Wheatpieces, or anywhere else in the GL20 area and you've got a drain that's behaving oddly, Drainsco covers Tewkesbury and the surrounding GL postcodes with engineers available 24/7. We'll give you a clear price before we start any work, there's no call-out fee, and our CCTV surveys produce a report you can actually use with a developer or a solicitor. Give us a call and we'll talk it through.