The short answer
Where the pipe is repairable, relining is usually less disruptive and often cheaper overall. Relining is a no-dig method: a resin-soaked liner is inserted into the existing pipe and cured to form a new pipe inside the old one, fixing cracks, root ingress and leaking joints without digging up the ground. Excavation means digging down to the damaged pipe and replacing the failed section — the traditional approach, needed when a drain has collapsed, badly deformed, or sits where relining cannot work. Relining wins on speed, surface disruption and reinstatement cost, since it avoids breaking up driveways, gardens and floors. Excavation is the fallback when the pipe is too far gone to line, or when a new connection or major realignment is required. A CCTV survey decides which is feasible.
Once a drain is damaged rather than just blocked, the choice is between repairing it from the inside or digging it up. Each suits different kinds of damage. Here is how relining and excavation compare.
Relining vs excavation
- ReliningResin liner inside old pipe
- ExcavationDig up and replace section
- DisruptionRelining low; excavation high
- SuitsReline: cracks/roots; dig: collapse
- Decided byCCTV survey
How each repair works
Drain relining is a trenchless (no-dig) repair. After cleaning the pipe, a flexible liner impregnated with resin is fed into the damaged drain from an access point, inflated against the pipe wall, and left to cure — often using ambient, hot-water or UV curing depending on the system. Once set, the liner forms a smooth, jointless new pipe inside the old one, sealing cracks, fractures and leaking joints and blocking the gaps where roots entered. A patch liner repairs a short defect; a full liner renews a whole length. Crucially, the ground above is never opened.
Excavation is the conventional dig-and-replace method. The contractor breaks the surface, digs down to the failed pipe, removes the damaged section and installs new pipework, then backfills and reinstates the surface. It is the direct fix and gives a brand-new pipe, but it is invasive: driveways, patios, gardens or floors above the run have to be broken up and made good afterwards, which adds cost and time.
| Factor | Relining (no-dig) | Excavation |
|---|---|---|
| Method | Resin liner inside pipe | Dig up and replace |
| Surface disruption | Minimal | High, breaks ground |
| Time on site | Often a day or less | Longer, depends on depth |
| Reinstatement cost | Little or none | Driveway/garden made good |
| Suits | Cracks, roots, leaking joints | Collapse, severe deformation |
| New connections | No | Yes |
| Result | New pipe inside old | Entirely new section |
Indicative comparison for guidance. Suitability confirmed by CCTV survey.
When relining is the better choice
Relining suits drains that are damaged but structurally still there — cracked or fractured pipes, drains with root ingress at the joints, leaking or slightly displaced joints, and general deterioration of an older clay or pitch-fibre run. Because nothing is dug up, it is far less disruptive: a driveway, patio, established garden, or a drain running under a building or floor can be repaired without tearing up the surface, which is often the deciding factor and a major saving on reinstatement.
It is typically quicker too, often completed in a day, and the smooth cured liner can actually improve flow and resist future root ingress. For the common scenario of an older pipe with cracks and root problems found on a CCTV survey, relining is frequently the lower-disruption and lower-total-cost answer once the cost of digging up and reinstating the surface is taken into account.
When excavation is necessary
Some damage is beyond lining. If a drain has fully collapsed, lost its shape, or deformed so badly that a liner cannot be installed against a sound wall, excavation to replace the section is the realistic fix. Excavation is also required where the work involves a new connection, re-routing the drain, correcting a serious fall problem, or replacing a run that has failed along most of its length rather than at isolated points. In those cases there is no intact pipe to line, so dig-and-replace is the appropriate method despite the disruption.
The way to decide between the two is a CCTV survey. The footage shows the condition of the pipe along its length and locates each defect, which tells the contractor whether a patch, a full liner or excavation is the right repair. A reputable firm will base the recommendation on what the camera shows rather than a default preference. Relining is the lower-impact option wherever the pipe can take a liner; excavation is the necessary route when it cannot, or when the work requires opening the ground anyway.
Patch repairs, full liners and responsibility
Relining is not a single technique but a family of them, and the right one depends on the defect. A localised patch or short liner repairs an isolated crack, fracture or open joint, sealing just that section while leaving the rest of the sound pipe untouched — quick, economical, and ideal where a survey shows a single point of damage. A full-length cured-in-place liner renews an entire run that has deteriorated along its length, forming a continuous new pipe inside the old one. A drainage engineer chooses between them based on the survey, and sometimes a combination is used along a longer drain with defects in more than one place.
Access is a practical consideration for both methods. Relining is carried out through existing chambers and access points, so it suits drains under driveways, patios, outbuildings and even under a property where digging would be hugely disruptive. Excavation needs working space above the pipe and a route to remove spoil and bring in new materials, which can be awkward in a tight garden or a paved area. Depth matters too: a deep drain is far more costly and disruptive to excavate than a shallow one, which often tips the balance toward a no-dig repair where the pipe can take a liner.
It is also worth confirming who is responsible for the damaged pipe before commissioning major work. A defect on a private drain within your boundary is yours to repair, but a problem on the shared lateral drain beyond the boundary or on a public sewer is usually the water and sewerage company's responsibility. Establishing this from the survey can save a significant sum, since you may not be liable for the repair at all. Where the drain is genuinely yours, choosing relining over excavation wherever the pipe allows keeps both the disruption and the total cost down.
Frequently asked questions
Is drain relining as durable as a new pipe?
A properly installed cured liner forms a strong, jointless pipe inside the old one and is designed to last for decades, sealing cracks and resisting root ingress. For repairable pipes it is a long-term fix, not a temporary patch. The key is that the host pipe must be sound enough to support the liner, which a survey confirms.
Can a collapsed drain be relined?
Generally no. Relining needs a reasonably intact pipe to form the liner against. A fully collapsed or badly deformed drain has no sound wall to line, so excavation to replace the failed section is usually required. A CCTV survey shows whether enough of the pipe remains to line.
Which is cheaper, relining or digging up the drain?
It depends on the damage and what is above the pipe, but relining is often cheaper overall once reinstatement is counted, because it avoids breaking up and making good driveways, gardens or floors. For a collapsed pipe that cannot be lined, excavation is the only option regardless of cost.
Sources & further reading
Figures on this page are typical UK ranges drawn from published cost guides and are intended as guidance, not a quotation.