Drain Relining vs Excavation Cost | The Real

A cracked or collapsed drain gives you two choices: line it from the inside without digging, or excavate, replace the pipe, and reinstate whatever was on top. Both work. The price gap between them, though, can be enormous, and the right answer isn't always the cheaper one.

I'll lay out the actual numbers, explain what's driving them, and tell you what I'd genuinely choose on my own house in different scenarios. Spoiler: it's not always the liner.

The Headline Figures

For a typical residential repair on a single run of 100mm drain between the house and the public sewer:

Those ranges are wide because conditions vary so much. Depth matters. Pipe material matters. What's on top matters most of all.

What Pushes the Cost Up

On the relining side

The resin liner itself is sold by the metre. Thin 100mm liner for a domestic drain costs far less per metre than a 150mm or 225mm section serving multiple properties. A straight run with clear access chambers is the cheap version. Add in bends, junctions, or a pipe that's badly deformed, and the price climbs because installation gets harder and slower.

Prep work is another variable people underestimate. You can't line a pipe that's half-blocked with root intrusion, grease, or debris. High-pressure water jetting and root cutting come first, and if the pipe needs it, that's extra time on the job. At Drainsco we don't skip that step because a liner installed over a dirty pipe fails early.

Cure time depends on the system. Hot-water or steam-cured CIPP (cured-in-place pipe) is faster than ambient-cure. UV-cured systems are faster still. Each has a different equipment cost, which feeds into the quote.

On the excavation side

Depth is the killer variable. A drain running 600mm deep under a back garden path is a couple of hours with hand tools. The same drain running 2 metres deep under a block-paved driveway in Monkspath or Dickens Heath is a different job entirely: shoring, a larger crew, careful lifting and relaying of the surface, proper compaction to avoid the drive sinking six months later.

Soil conditions in the Solihull area vary too. Sandy loam in parts of Knowle and Dorridge is easy to dig. Heavy clay in Chelmsley Wood and Kingshurst is slower, and collapsed trenches in wet weather add risk and time.

Reinstatement is the cost that often doesn't appear in the initial quote you get from a company that subs out the surfacing work. Always ask whether the price includes like-for-like reinstatement of the surface. Block paving, pattern imprinted concrete, and natural stone can cost more to reinstate than the drain repair itself.

Why the Survey Has to Come First

I'll be straight about this: any company that quotes you for either option without a CCTV survey first is guessing. They might guess right, but you have no way of knowing that.

A survey shows the exact nature of the defect, its location, the pipe's condition along its full run, and whether there are access points that make relining practical. It also shows whether the pipe is so badly deformed that a liner can't be pulled through, which is the situation where excavation wins regardless of cost preference.

The survey cost sits between £150 and £300 for a standard residential job. If you end up booking a repair through the same company, a good few will credit it against the job. If they don't, it's still money well spent because you're buying certainty.

The Honest Trade-off

Relining is almost always less disruptive and usually cheaper when the pipe is in decent enough shape to take a liner. The 20-year guarantee you get on properly installed remedial work is meaningful, not marketing. A liner that's correctly installed, well-prepped, and fully cured is a new pipe inside the old one. It won't corrode, it resists root re-entry better than a plain clay joint, and the flow characteristics often improve because the bore is smooth.

Excavation wins in these specific situations:

• The pipe has collapsed completely (a liner needs something to form around)
• The bore is deformed by more than about 15 to 20 per cent of its original diameter
• There's a belly in the pipe, meaning a section has dropped and holds standing water. A liner follows the existing profile; it doesn't lift the pipe back up
• You need to increase the pipe diameter
• There's a junction defect that's genuinely inaccessible to a lateral cutter and can't be patched cleanly
• The pipe is on a gradient so steep that liner installation becomes unreliable

For a detached house in Shirley or Olton with a single clay drain from circa 1960, running under 15 metres of garden at a sensible gradient, with two access chambers, relining is almost always the right call. The numbers are lower, the garden stays intact, and the job is done in a day.

For a terrace in Kingshurst or Smith's Wood where the drain is already 1.8 metres deep, runs under a shared path, and the CCTV shows a full collapse in two places, dig it up. Trying to reline a pipe in that state wastes money.

The Maths on Disruption

Cost comparisons don't capture disruption well, so here it is in plain terms.

Excavating a 6-metre run under a tarmac driveway in Bentley Heath typically means:

• The drive is inaccessible for 2 to 5 days
• Some surface disturbance remains visible for weeks while the ground settles
• You need a skip or muck-away, which is another cost and another vehicle on your road
• In a Dickens Heath or Hillfield estate, getting a skip permit can add a day's wait

Relining the same run means one van outside for a day, a jet wash of the chamber before and after, and no reinstatement at all because nothing was dug up. The grass still looks the same. The block paving is still level. The drive is usable the same afternoon.

For landlords managing rental properties in Marston Green or Castle Bromwich, that difference in disruption has a real value: the property stays habitable, no tenant is dealing with a front garden that looks like a battlefield.

What I'd Actually Choose

On my own house, assuming the CCTV showed a cracked but geometrically intact clay pipe with root intrusion and a couple of open joints over a 12-metre run:

I'd reline it. Every time.

The roots are coming back if I excavate and lay new pipe with rubber-jointed PVC, because the tree causing the problem is still there. A CIPP liner removes the joint gaps that roots exploit in the first place. The garden stays untouched. The job is quicker. And the guaranteed working life on the remedial work gives me real protection.

If the survey showed a 400mm-deep pipe with a complete collapse in the middle, I'd excavate and replace that section. Not because I want to, but because there's no honest argument for anything else.

The honest answer to the question most homeowners are really asking, which is 'how do I spend the least and get the most reliable result?', is: pay for the survey, get a diagnosis, then let the diagnosis tell you which method to use. Don't go looking for a liner company or an excavation company. Go looking for a company that does both and is willing to tell you which one your drain actually needs.

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Drainsco covers Solihull and the B postcodes from B37 to B94, with engineers available 24 hours a day. There's no call-out fee, and you'll get a clear price before any work starts. If you want to understand what's actually happening underground before committing to a repair, a CCTV survey is the right starting point. Give us a call and we'll tell you what we find.