When an embankment on the Llangollen Canal collapsed in the early hours of December 22nd 2025, it made headlines around the world. But canal breaches are nothing new, and understanding why they happen, and what it takes to fix them, reveals just how precarious Britain’s 200-year-old waterway network really is.
The site of the breach – thanks to Nick Grundy for use of the image
A Breach Like Any Other?
Canal embankment collapses are not that unusual. There have been probably been about 400 recorded ‘breaches’ since 1888, according to the National Breach Archive, on average of four or five every year, and remarkably consistent over 150 years.
Embankments have always been the canal engineer’s big headache. The great canal builders tried to avoid them by following hillside contours — James Brindley’s winding routes are the classic example. Thomas Telford took the opposite approach, driving his canals in straight lines using embankments and cuttings. It nearly broke him. The mile-long Shelmore Embankment on the Shropshire Union Canal plagued him until his death: each time it was built it collapsed. It was completed two years late, massively over budget, and is still subsiding by five millimetres each year.
Despite those early struggles, Britain’s canals now contain hundreds of miles of embankments — an essential part of a system that must keep water level across varied terrain. The Canal and River Trust (CRT), the charity responsible for managing around 2,000 miles of waterway in England and Wales, considers embankments its highest-risk asset category. Four or five breaches a year, every year, is simply the cost of keeping the network working.
What Happened at Whitchurch
In the early hours of 22nd of December last year, a section of embankment carrying the Llangollen Canal near Whitchurch, Shropshire, gave way. Some reports quickly dubbed it a ‘sinkhole’, an underground void which eventually collapses. It is unlikely to have resulted from a sinkhole, though the cause has yet to be officially revealed.
One common cause of breaches which can be discounted is ‘overtopping’ where the water level on the embankment rises suddenly because of torrential rain or lock gates left open or paddles left raised. Water overflowing the embankment at a low spot can create a rapidly deepening channel in the side of the embankment, but this would have resulted in a pattern of collapse not seen here.
Possible causes include heavy rain undermining the structure or a culvert beneath the embankment collapsing. Something called ‘piping’ can occur when a channel slowly develops, leading to leaks through the canal side or bottom. This could be due to badgers or rabbits digging tunnels, tree roots rotting away or steel piling deteriorating. A long-standing structural weakness could be due to poor construction materials being used in the embankment. Canal engineers were learning on the job 200 years ago, using whatever materials were handy!
The consequences of the breach were significant but, fortunately, not catastrophic. Fifteen people were evacuated, seven narrowboats were affected, and a field of pasture was flooded. Nobody was killed or seriously hurt. Three boats were left stranded in the mud at the base of the collapsed embankment — their recovery would prove to be a complex and painstaking operation. One might have to be scrapped.
There was much public sympathy, expressed partly through a crowdfunding appeal. Intended to raise just a few thousand pounds for emergency replacement belongings and shelter for a few homeless boaters, it actually raised over £100,000!
The broader consequences to the canal network were more serious. The Llangollen Canal is one of Britain’s most popular leisure waterways, and the breach severed it from the wider system. Boaters were locked on the upper Llangollen, unable to join the rest of the canals, or unable to access the upper section. Canal businesses were cut off from their customers. CRT has a contract to maintain water supplies to Hurleston Reservoir which now needs multiple huge pumps running 24 hours a day.
Given these serious effects it might be expected that CRT would have an explanation for the breach. Their CEO, Campbell Robb, was reported as saying that it was important that lessons are learned from this collapse before the rebuild but went on to caution that the full cause may never be fully understood. It is certainly true that most engineering failures may have a number of contributary causes; often an underlying weakness is stressed by an unusual event. But CRT engineers have data from the National Breach Archive, an official database going back to 1888, which contains records of over 400 canal embankment collapses. However, his caution may be strategic; engineering failures have legal and financial implications when responsibility is being allocated. Reduced standards of inspection or maintenance have been suggested as possible contributory factors, with local reports that water had been running from the Whitchurch embankment for months before the collapse.
Narrowboat Sefton may have to be scrapped – thanks to Jim Forkin IWA for use of the image
The Recovery Operation
Fixing a major breach is never straightforward. Before any permanent repair can begin, engineers need to install temporary dams to manage the remaining canal water, divert flows to maintain any water supply obligations, and create safe working access across what is often waterlogged and unstable private land.
At Whitchurch, the three stranded narrowboats had to be recovered before embankment reconstruction could begin. This required specialist contractors and some remarkable equipment: off-road recovery cranes, heavy tracked winches, and a ‘spider excavator’ — a machine with four large wheels on flexible arms, allowing it to step freely in and out of the drained canal. Non-elastic tow cables were used to drag the boats clear up specially constructed muddy ramps, ensuring that if a cable snapped it would drop safely rather than recoil with lethal force.
The total cost of the repair has been estimated at £5 to £7 million. The rebuild itself — probably involving replacing around 5,000 tonnes of embankment material— is expected to take the rest of the year. Online commentators question why reconstruction should take twelve months when historical rebuilds sometimes took only a few weeks with just men and wheelbarrows. Of course construction today requires lengthy planning, being far more bound by legislation covering standards and health and safety. And CRT no longer have a large workforce and infrastructure, outside contractors doing most of the rebuilding. And importantly in today’s financial climate CRT must choose the most affordable repair, not necessarily the fastest. So the boats have to wait!
With luck, narrowboats will be cruising across a rebuilt Whitchurch embankment before the year is out. However the questions raised by this breach about the long-term condition of Britain’s canal network will not be so easily resolved.
We consider those questions and implications in ‘The Narrowboats that Circled the World’.
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