Pipe Relining vs Excavation: Which Drain Repair Method Is Right for You?

When a CCTV survey confirms that a drain has failed structurally — a crack, a collapse, root ingress at multiple joints, a displaced section — the conversation shifts from clearing the blockage to repairing the pipe. Two methods dominate that repair work in the UK: cured-in-place pipe relining, and traditional open-cut excavation.

There is no single right answer. Each method has situations where it is clearly the better choice, and situations where the other is. This guide explains how both work, where each is appropriate, and the questions to ask before committing to a repair.

How Pipe Relining Works

Cured-in-place pipe (CIPP) lining creates a new pipe inside the old one, without digging. The process, in simplified form:

1. The failed section is jetted clean and surveyed on camera to confirm it is a candidate for lining.
2. A flexible felt or fibreglass sleeve, impregnated with a two-part epoxy or polyester resin, is fed into the drain from an existing access point — typically a manhole.
3. Compressed air or water inverts the sleeve so the resin-saturated side presses against the pipe wall.
4. The resin cures — either by ambient temperature, hot water, or UV light depending on the system — forming a hard, seamless, jointless pipe inside the host pipe.
5. Any junctions (where a branch drain joins the main run) are reopened using a robotic cutter.

The cured liner is structurally independent. Even if the outer clay pipe continues to deteriorate around it, the liner continues to function as a standalone pipe.

A typical domestic lining job in Merseyside takes one working day. Our pipe relining service uses ambient-cure and UV systems depending on access and run length, and carries a 10-year guarantee with a manufacturer-stated design life of 50 years.

How Excavation Works

Open-cut excavation is the traditional method. The failed section is located precisely by CCTV and sonde tracing, the ground above is broken out, and the damaged pipe is removed and replaced with new PVC or clay pipework laid on a proper bedding material and backfilled in compacted layers.

The process sounds simple but rarely is. A 2-metre-deep drain in a Victorian terrace garden in Liverpool or Birkenhead requires trench supports, spoil storage somewhere on a narrow plot, careful protection of shared walls and boundary fences, and reinstatement of whatever surface the trench crossed — slabs, tarmac, decking, lawn. Where the drain runs under a conservatory, driveway, kitchen extension, or the public highway, the complications multiply.

For the full process and scope of what an excavation involves, see our drain excavation service page.

When Relining Is Appropriate

Relining is the right choice when:

• **The pipe is broken or cracked but still holds its shape.** Fractured joints, longitudinal cracks, open joints with root ingress, localised patch damage — all reline well.
• **The internal diameter is largely intact.** The liner adds 3–6mm of wall thickness, so the starting pipe must not already be significantly constricted.
• **Access is possible from manholes at both ends.** Lining needs an installation chamber and a take-off chamber.
• **The affected run is a reasonable length.** Lining is economic for runs of 3 metres upwards; below that, a patch liner or spot repair is usually more appropriate.
• **The surface above is valuable or hard to reinstate.** A drain under a block-paved drive in Crosby, a mature lawn in Huyton, or a freshly-laid extension floor is far cheaper to line than to dig.

When Excavation Is Appropriate

Excavation is the right choice when:

• **The pipe has collapsed or deformed by more than about 10–15%.** A liner cannot recover a crushed profile; it simply hardens in the deformed shape, which does not restore capacity.
• **A section is completely missing.** You cannot line through an open cavity — the liner needs a pipe wall to press against.
• **There is severe offset or bellying.** A pipe that dips or "bellies" in the middle holds standing water. Lining it preserves the belly; excavating and re-laying to proper falls eliminates it.
• **The pipe material or diameter needs to change.** For example, upsizing from a 4-inch to a 6-inch run, or removing a length of undersized lead.
• **Access for lining is impossible.** No manhole at one end, or the run passes under a structure that will not allow a lining rig to set up.

Cost Comparison

Costs in Merseyside in 2026 typically fall within these ranges for a straightforward domestic job:

• **Patch lining a single joint:** £600–£1,200 depending on depth and access.
• **Full relining a 10-metre domestic run:** £2,400–£4,500.
• **Excavating and replacing a 2-metre section at 1m depth in an accessible garden:** £1,800–£3,500.
• **Excavating and replacing the same section at 2m depth, under a driveway with reinstatement:** £4,500–£9,000 or more.

The headline comparison — "lining is cheaper than digging" — is true more often than not, but not universally. A shallow drain in open garden is frequently cheaper to excavate than to line. A deep drain under a conservatory is always cheaper to line. The cost of the repair itself is rarely the whole story; reinstatement of the surface above often costs more than the groundworks, which is where lining wins decisively.

For broader context on drainage pricing in the region see our guide on drain unblocking costs in Liverpool.

Disruption Comparison

This is where the two methods diverge most visibly.

A relined drain in a Bootle terrace typically involves a van and a trailer on the street, access to the rear manhole for half a day, a curing period of 2–6 hours, and a post-cure CCTV inspection. Nothing is dug up. The garden, paving, and planting remain untouched. The household can usually continue to use upstairs fixtures during the cure by arrangement.

An excavation of the same drain involves a mini-digger or hand-dig, spoil heaps, plywood trench protection, and several days' work before reinstatement begins. Use of the drain is suspended for the duration. If the trench crosses paving or tarmac, the surface will never quite match what was there before — reinstatement aims for functional, not invisible.

For households in Kirkby, St Helens, or Widnes where the drain is in a side garden with straightforward access, the disruption gap narrows. For dense urban terraces with rear shared entries, lining is in a different league.

Guarantees and Lifespan

Both methods, properly carried out, produce a 50-year solution.

A CIPP liner installed to WIS 4-34-04 with an approved resin system has a documented design life of 50 years and is routinely guaranteed by installers for 10 years. New PVC pipework installed to BS EN 1401 and bedded correctly has the same expected lifespan.

The lifespan you actually get depends far more on workmanship than on the method. A poorly-prepared liner with inadequate pre-clean will delaminate within a year; a poorly-bedded replacement pipe will sag and block within five. Choose the installer on the basis of their survey quality and their willingness to explain the decision, not on a headline price.

How a CCTV Survey Informs the Decision

No reputable drainage company will quote a reline-or-excavate job without a CCTV survey. The survey tells us:

• The exact defect type, location, and severity.
• The pipe material, diameter, and condition along the whole run.
• The gradient, identifying bellies that affect the lining decision.
• The location of junctions that will need reopening post-liner.
• Depth and access, which drives both cost and method.

We provide the survey report and video footage to the customer as standard, which allows you to get second quotes on a like-for-like basis. Buying drainage repairs without a survey is like buying a car without opening the bonnet — you will be relying entirely on the word of whoever is pricing the job.

For homebuyers facing this decision during a purchase, our guide on CCTV drain surveys for home buyers explains how to factor drainage defects into negotiations.

The Short Version

• **Cracks, joint failures, root ingress, most patch damage** → reline.
• **Collapse, severe deformation, missing sections, bellying, upsizing** → excavate.
• **Mixed defects** → often a combination: excavate the collapsed section, reline the rest.
• **Under a hard surface, a structure, or the highway** → reline if at all possible.
• **Shallow, open, accessible garden** → excavation is often cheaper.

If you have a CCTV report from another contractor and want a second opinion on the recommended method, Blocked Drains Liverpool will review the footage free of charge and give you a fixed-price quote on either basis. Call 0333 323 2242 — we cover all of Merseyside, from Wirral to Knowsley.