Drain Relining vs Excavation Cost | Which Is Right for You

A broken drain puts most homeowners in the same position: someone tells them it needs digging up, and they nod along because they don't know enough to push back. Sometimes digging is exactly right. Plenty of times it isn't. The choice between relining a pipe and excavating it is genuinely consequential, not just for your wallet but for your garden, your driveway, and however many weeks of disruption you're willing to stomach.

This piece runs the numbers on both options, explains what moves the price in either direction, and tells you honestly which one I'd choose on different types of job. I've rerouted and relined drains under listed buildings in Cirencester's town centre, under block-paved drives on Chesterton, and under concrete slabs on industrial units out towards Kemble. Each scenario looks a bit different.

What the Numbers Actually Look Like

First, a table. The ranges here reflect what jobs genuinely cost across Gloucestershire, factoring in ground conditions, pipe diameter, access, and depth. They're not plucked from a price list.

The headline is simple: relining is almost always cheaper when access is the expensive part. Excavation wins when the pipe is so far gone that a liner has nothing to bond to, or when the run needs complete rerouting.

How Relining Actually Works

Cured-in-place pipe lining (CIPP) is the method we use. A felt tube saturated with epoxy resin is inverted or pulled into the damaged pipe, inflated against the host pipe walls with an internal bladder, and held there while the resin cures. Depending on pipe diameter and ambient temperature, that takes two to four hours. Once cured, the bladder's deflated and removed. What's left is a smooth, jointless sleeve that bonds to the inside of the old pipe and effectively becomes a new pipe within the old one.

The inside diameter drops slightly, usually by 6–10 mm on a standard 100 mm drain. In practice that's irrelevant for residential flow rates. The liner itself is rated to handle the same pressures as a new clay or PVC pipe, and properly installed it'll outlast most of the house around it.

No trench. No reinstatement. No skip on the drive for a fortnight.

How Excavation Actually Works

You already know the broad strokes: dig down to the pipe, break it out, lay a new section, backfill in layers, reinstate the surface. The devil is in the detail.

Depth matters enormously. A pipe at 600 mm in light soil is a half-day job for two engineers. That same pipe at 1.8 m in clay, near a building foundation, under an adopted footway in Watermoor or the Beeches, is a multi-day operation with shoring boards, a larger machine, possible traffic management, and a highway reinstatement done to Gloucestershire Highways spec. The cost multiplies fast.

Ground conditions in Cirencester aren't uniform. The Churn valley has some genuinely heavy clay. Older parts of the town, around Watermoor Road and the Abbey, have made ground with rubble and Victorian infill that can surprise you. Out towards South Cerney and Down Ampney, you're sometimes working through gravel. Each changes the excavation cost.

The other thing excavation can't avoid is reinstatement. A dug drive comes back looking almost right, but almost right is usually visible. Block paving that's been lifted and relaid sits slightly differently. Concrete never matches. If your driveway or patio matters to you aesthetically, that's a real consideration.

What Actually Drives the Price Up

For relining:

• Pipe condition. The liner needs enough of the host pipe to bond to. Collapsed sections, heavily displaced joints, or severe root intrusion that's fractured the pipe wall may need a short excavation to expose the problem point before a liner goes in either side.
• Bends and junctions. A straight run is simplest. Multiple changes of direction or a complex junction arrangement means specialist lateral-cutting equipment after lining, which adds cost.
• Diameter. 100 mm household drain: standard kit, standard price. 150 mm or 225 mm commercial or shared drains cost more because the liner material is more expensive and the equipment's larger.
• Pre-lining jetting. The pipe has to be scrupulously clean before a liner goes in. Root-cutting and high-pressure jetting beforehand is non-negotiable and adds time. Some contractors quote it separately. Make sure yours is upfront about that.

For excavation:

• Depth and shoring. As above. A pipe at 2 m-plus needs shoring by law. That's equipment, time, and complexity.
• Surface reinstatement. This is routinely underquoted. Get a fixed price that explicitly includes breaking out and making good to the original standard, not just backfilling to formation level.
• Disposal. Contaminated soil or old asbestos-cement pipe (more common on pre-1980 properties in central Cirencester than people think) incurs disposal costs that can add hundreds.
• Traffic management. If the pipe's under a shared or adopted surface, you may need a road closure permit and traffic management. That's a fixed cost regardless of pipe length.

When I'd Choose Relining

Honestly, relining is my default recommendation for most residential jobs in and around Cirencester, and here's why:

The majority of failures I see on CCTV surveys are cracked joints, tree root infiltration, partial fractures, and pipe deformation. None of those require full replacement. A liner addresses all of them, permanently, without a single shovelful of soil moved. On a typical semi-detached in Stratton or Four Acres, where the drain runs under a concrete path to a manhole near the front boundary, the thought of breaking that path up, digging down, relaying the path afterwards, and having the owner live without their parking space for a week is genuinely unnecessary if a liner will do the job.

I'd especially push for relining under any adopted surface, under mature trees (excavating close to established root systems causes its own problems), and in any conservation area or near listed buildings where groundworks attract additional scrutiny.

When Excavation Is Actually the Right Call

There are real situations where a liner won't cut it.

• Complete collapse. If the pipe has lost its circular profile entirely, there's no void to invert a liner into. A short dig is unavoidable.
• Bellying or negative gradient. A pipe that's settled and now runs uphill in places holds water and solids permanently. Relining a sagged pipe just gives you a smooth-walled sump. The gradient needs fixing, and that means excavation.
• Wrong pipe material for bonding. Very old pitch-fibre pipe (that spongy, slightly oval stuff from the 1950s and 60s) can be poorly suited to standard CIPP lining because the surface is too unpredictable. Some contractors will still line it; I'd want to assess it properly first.
• Rerouting. If the drain needs to go somewhere different, whether to accommodate an extension, to comply with a building regulations condition, or because the existing route is irredeemably compromised, you're digging regardless.

Neither method is universally superior. The pipe tells you which one it needs, and the pipe doesn't reveal that until you've looked at it properly.

Why the Survey Has to Come First

Every cost I've given above assumes someone has already done a CCTV drain survey and knows exactly what's in the ground. Without that, any quote is essentially a guess, and the contractor is pricing in their uncertainty, usually upward.

A CCTV survey on a residential drain run typically costs £150–£350 in this area. It gives you a video record of every crack, root, joint displacement, and change in gradient. It tells you the pipe material, the condition of every junction, and precisely where any problem starts and ends. That information is what makes a lining quote accurate. It's also what prevents you from paying to reline a 6 m section when the real problem is a 1 m collapsed section further along that you didn't know about.

If a contractor quotes for relining or excavation without first putting a camera down the pipe, that's a red flag. Not because they're necessarily dishonest, but because they genuinely cannot price it accurately.

At Drainsco we always survey before we quote on remedial work. The survey findings are explained to you on the day, you get a copy of the footage, and then you get a fixed price for whatever the repair requires. No surprises once we're on site.

How to Spend the Money Sensibly

If your drain is giving you trouble, the sequence that makes financial sense is:

1. Get a CCTV survey done. Don't skip this to save £200 and then spend £1,500 on the wrong repair.
2. Ask for the survey report in writing, with footage. It's your pipe and you're entitled to the evidence.
3. Get a fixed quote for the remedial work with reinstatement included and the method clearly specified. Not a day-rate. A fixed price.
4. If relining is quoted, confirm the liner carries a proper guarantee. Ours carries a 20-year guarantee on remedial work.
5. If excavation is quoted, make sure the price explicitly covers breaking out, backfilling to specification, and surface reinstatement. Get that in writing.

That process protects you whether the answer is a liner or a digger. The contractor who resists any part of it is telling you something.

Drainsco covers Cirencester and the GL7 postcodes, with engineers available 24 hours a day. There's no call-out fee, and we won't start work without giving you a clear price first. If your drain needs looking at, a call takes five minutes and we can usually get a camera on it quickly.