Thirlmere aqueduct and reservoir


Duration:4 years


Country: Manchester, UK

What did this project achieve?

In Victorian times build the longest aqueduct ever to supply Manchester with water

Thirlmere aqueduct is the longest aqueduct in Britain. It transports water 153km from Thirlmere reservoir in the Cumbrian hills to Manchester. It can carry up to 227m litres of water a day.

Both the aqueduct and reservoir opened in 1894 after 4 years construction work.

Thirlmere is the longest gravity-fed aqueduct in Britain – there are no pumps along the route. Water flows at about 6km an hour and takes just over a day to reach the city.

The aqueduct runs in tunnels for around 80km and through cast iron pipes for another 72km. The first tunnel at the start of the route is the longest at 5km and runs under Dunmail Rise.

Thirlmere reservoir's dam is 261m long with a maximum height of 20m. There's a 5m wide road along the top between stone parapet walls. It can hold up to 39,000m litres of water.

The aqueduct and reservoir were designed and built by engineer John Frederick Bateman. Bateman's work is acknowledged as the cornerstone of Britain's water supply industry.

Bateman worked with his pupil and later business partner George Henry Hill on both projects.

Difference the reservoir and aqueduct have made

The Thirlmere reservoir and aqueduct have supplied water to Manchester for over 120 years.

The project played a large part in the continuing urbanisation of Manchester in the late 19th and early 20th centuries. It contributed to the infrastructure of one of the UK's leading cities.

The reservoir and its surroundings have become a recreational venue, popular with cyclists and hikers.

How the work was done

Engineers working on Thirlmere aqueduct used the 'cut and cover' method for 58km of the aqueduct's length.

'Cut and cover' means workers dug out a D-shaped trench in the ground and then covered it over with a roof of earth. Newly created lengths of tunnel were lined with brickwork.

The aqueduct runs in tunnels dug below ground for 22km. The longest section was dug under Dunmail Raise, a mountain pass close to the reservoir.

This section of the tunnel was constructed by 2 teams of workers digging towards each other from different directions. The centres of each tunnel are said to have met within 20cm of each other.

The aqueduct runs through cast iron pipes for 72km of its length. Another 3 pipes were added between 1904 and 1927.

Engineers gave each of these new pipes an 'equilibrium float valve' at its inlet. The valves were designed to trip shut if the water flow suddenly increased – if a pipe burst, for example.

Workers building the dam at Thirlmere reservoir used concrete and masonry to construct the 261m long structure.

The core of the dam consists of large rocks – known as plums – embedded in concrete. Annan sandstone was used for the downstream face of the structure and Longridge stone on the upstream face.


John Frederick La Trobe Bateman: pioneer and water engineer extraordinaire… brought water to the taps of Tameside and Manchester.

From a plaque to Bateman

on the deepest air shaft of the Mottram tunnel, a pipeline connecting the Etherow and Tame valleys, unveiled in 2000.

Fascinating facts

As well as creating water systems for Manchester, Bolton and Oldham, John Bateman worked extensively abroad. Overseas projects included the design of water and drainage systems for the cities of Naples, Constantinople and Buenos Aires.

In 1883 Bateman assumed his mother's family surname of La Trobe by royal licence to become the rather grander-sounding John Frederic La Trobe Bateman.

Bateman was president of ICE in 1878 and 1879.

People who made it happen

  • Consulting engineer: John Frederick Bateman, ICE President
  • Associate engineer: George Henry Hill

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