Collapsed drain repair

Rodding cleared your drain last month and it is blocked again today. That pattern usually means the pipe has failed rather than blocked. This page tells you how to be sure, and what the repair involves. A collapsed drain is a section of underground pipe that has cracked, caved in or broken apart.

Waste can no longer pass through it. No amount of rodding or jetting will clear it. Drainage Emergency confirms a collapse with a closed-circuit television (CCTV) survey. Then it repairs the drain.

It lines the pipe where it can be reformed, or digs down and replaces the section where it cannot. We cover Derby, Derbyshire and Nottinghamshire, 24/7, on 01332 215521.

Signs your drain has collapsed rather than blocked

A blockage clears and stays clear. A collapse clears for a while, then comes back, because the pipe itself is the obstruction. These are the signs we are asked about most, and what each usually means.

• Blockages that keep coming back after rodding or jetting, the most reliable sign that something structural is catching solids
• A sewage smell that will not go, near a manhole, in the garden or indoors, because waste is escaping the pipe
• A dip or soft patch in the lawn, patio or drive over the line of the drain, where escaping water has washed the soil out
• Damp or mould low on a wall with no plumbing above it
• Rats, because a broken drain is an open door
• Gurgling from a toilet or sink when something else drains, as air is pushed back through a partial collapse

One of these on its own can have another cause. Two together, on a house with clay drains, is worth a survey.

Why drains collapse in Derby

Age is the main reason. The late-Victorian terraces around the Arboretum are on their original salt-glazed clay drains with rigid joints. The Arboretum opened in 1840 as England’s first purpose-designed public park. Clay lasts, but the joints do not flex.

After a century of ground movement, traffic and root pressure, the collar (the socket where one pipe joins the next) fractures. The next section then drops. A dropped joint catches solids, the pipe fills, and the ground around it softens until the section gives way.

Tree roots do the same job faster. They find the moisture at a joint, force it apart, and the pipe cracks around them.

The 1950s and 1960s estates in Sinfin, DE24, beside the Rolls-Royce site, fail differently. Concrete and clay drains are now at the age where joints displace. That is a collapse in the making, rather than a collapse yet. Spondon’s old village core, DE21, still has some of the oldest private drainage in the east of the city. It fails the way the Arboretum terraces do.

Confirming a collapse: clear it, then survey it

We do not diagnose a collapse from the surface. Nobody should. The engineer first clears whatever can be cleared, usually with high-pressure water jetting, so the camera has a run. That is the same emergency drain unblocking visit as for any blockage, and sometimes that is all it was.

Then the camera goes in. A CCTV drain survey shows whether the pipe is cracked, displaced, holding water or fully collapsed. It also measures the distance to the defect from a known inspection chamber, the manhole on your drain. If the camera cannot pass, where it stops and what it sees there is the diagnosis.

You get the footage and a written report. It says what has failed, where, how deep, and which side of your boundary it sits on.

Everything that follows comes off that report.

How a collapsed drain is repaired

There are two routes, and the survey decides between them.

The pipe might still have its shape, even with cracks, open joints or a partial drop. If so, it can usually be reformed from the inside. The trade calls this relining. A resin-soaked liner is inserted through an existing chamber.

It is inflated against the pipe wall and cured in place. This forms a new pipe within the old one without disturbing the surface. For a short failure a patch does the same over one section. Our drain repair page explains relining and patch repair in full.

The pipe might have gone flat, have a section missing, or have dropped so far that the camera cannot pass. If so, there is nothing for a liner to follow. The failed section then has to be dug out and replaced with new pipe.

That new pipe is jointed to sound pipe on either side, and the ground reinstated. It is the repair nobody wants. We recommend it only when the footage shows a liner would not hold, and you see that footage first.

Collapsed drains under old terraces and in conservation areas

Darley Abbey, DE22, is a conservation-area mill village on the Derwent and part of the Derwent Valley Mills World Heritage Site. The Georgian mill-workers’ cottages around Darley Abbey Mills were founded by the Evans family in 1782. They have the oldest drainage in the city.

They also carry strict rules on external works. A no-dig liner is the first choice here because it never opens the ground. Where a dig is unavoidable, the reinstatement has to respect the setting, and we say so at the quoting stage.

The Victorian terraces around the Arboretum in DE23 have a different complication: shared runs. A drain often passes under two or three neighbours before it reaches the sewer. A collapse under one yard can show up first as a blocked toilet next door. The repair may need a neighbour’s access, or it may not be yours to pay for.

Who pays for a collapsed drain

It depends on which side of your boundary the collapse sits.

Severn Trent Water owns the public sewers in Derby. Since the 2011 transfer of private sewers, it is also responsible for most pipework beyond your property boundary. It is also responsible for shared drains serving more than one property. A collapse on a shared run under a terrace is normally theirs. A collapse on the drain that serves only your house, inside your boundary, is yours.

Buildings insurance often covers accidental damage to underground drains, and the cost of tracing the fault. But wear and tear, root damage and poor maintenance are commonly excluded. Read your policy, then book the survey: the report and footage are what the claim will rest on.

A collapsed drain can be the cause of subsidence rather than a result of it. Water escaping from a broken pipe washes the fine soil out from beneath a wall, and the wall settles. If you have cracks and a drain problem together, get the drain surveyed first.

What happens when you call

Call 01332 215521, 24 hours a day, 365 days a year. Tell us what you are seeing, where the nearest chamber is if you know, and whether anything is backing up now.

If waste is backing up, the first visit is an emergency clearance and the survey follows once the run is clear. If not, the first visit is the survey. Either way you get the report and the footage.

Then a quote sets out the method and the price, with no hidden fees. For quotes under two thousand pounds you pay only when the work is complete. We work from Mansfield Road, DE21, and carry £5 million public liability insurance, covering Derby, Derbyshire and Nottinghamshire.

Customers regularly report our engineers arriving within the hour. One wrote that Chris cleared and surveyed his drains over a weekend. Phil and his team then had the run relined by the Wednesday. A collapsed drain is rarely that quick, but it starts the same way. Call 01332 215521, and the next thing that happens is an engineer with a camera, not a guess.