Drain Relining Explained

How the process actually works

The run is first jetted clean to bare pipe wall, because a liner will not bond to fat, scale or silt. Roots are cut out and any protruding intrusions are removed with a cutting head. The run is then surveyed again to confirm it is clean and to measure the exact length and diameter required.

A felt or fibreglass liner is impregnated with resin, inverted or winched into position, and inflated with an air or water bladder so it presses tight against the host pipe. It is then cured, either by leaving it to set, by circulating hot water or steam, or by drawing an ultraviolet light train through it. Once cured the bladder is removed, any branch connections are reinstated with a robotic cutter and a final CCTV inspection records the finished job.

What relining suits

• Cracked and fractured pipes where the shape is broadly intact.
• Open or displaced joints that keep catching waste.
• Root ingress, because the liner seals the entry point permanently.
• Runs under driveways, garages, extensions, patios and mature planting.
• Long runs where excavation would mean multiple trenches.
• Properties where access for a digger is impossible or would cost more than the repair.

What it does not fix

A fully collapsed pipe has no host structure to line against, so there is nothing to hold the liner in shape. Severe deformation, where the pipe has been squashed well out of round, has the same problem, and a badly displaced joint where one pipe has dropped clear of the next cannot be bridged by a liner alone.

It also cannot correct a fall problem. If a section has settled into a dip, lining it produces a smooth, watertight dip, and solids will still drop out of suspension in the same place. That case needs excavation and relaying at the correct gradient, and any contractor who offers to line a fall problem is selling you a repeat visit.

Timescales and disruption

A single patch repair is typically a half day job. A full length liner on a domestic run is usually a day, occasionally two where cleaning is heavy or where several branches need reinstating. In almost all cases the work happens through existing chambers, so nothing is dug, no driveway is lifted and the garden is untouched.

Drainage is generally out of use for a few hours while the liner cures. We work around that by phasing the work and, on commercial sites, by carrying it out outside trading hours.

Life expectancy and the small loss of bore

A properly installed cured in place liner is generally expected to last around fifty years, which comfortably exceeds the remaining life of most of the clay it is installed inside. The finished surface is smoother than clay, so flow performance often improves despite a small reduction in internal diameter, typically a few millimetres on a domestic pipe.

That trade off only becomes relevant in a run that was already marginal on capacity, which is rare on domestic drainage and something we would flag before quoting on a commercial system.

How the decision gets made

It is made from the survey footage, not from a guess on the doorstep. The camera shows whether the host pipe still holds its shape, whether the fall is sound and whether the defect is one length or several, and those three facts determine patch, full liner or excavation.

We carry out all three methods ourselves, which means there is no commercial reason for us to steer you towards one. Where excavation is genuinely the right answer we will say so, and where a driveway can be saved we will save it.

Preparing for a lining visit

There is very little for you to do. We need access to the chambers at each end of the run and space for the van, and we ask that water use is kept to a minimum for a few hours while the liner cures. Nothing is dug, so gardens, driveways and planting are left as they are.

On a commercial site we schedule the curing window outside trading hours. On a domestic property we phase the work so a household is not without a toilet for a full day, which usually means starting early and having drainage back in use by the afternoon.

Questions we get asked