The 5 biggest reservoirs in the UK

The Kielder Reservoir is the biggest in the UK by volume of water
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Everyone loves a reservoir and as we say here at PipeRepair.co.uk, the larger, the better – so in honour of those massive bodies of water which both supply and conserve, we have put together this list of the five biggest reservoirs in the UK.

Some started out as natural lakes before having their water levels increased. Others were 100 percent manmade. Most of them swallowed up farms, villages, schools or churches and several remain hugely controversial more than half-a-century after being constructed.

What this list also proves is that reservoirs provide so much more than water. They are great for the environment, water sports, as renewable sources of energy, and even as tourist attractions.

Llyn Brianne

Kicking off our list of the five biggest reservoirs in the UK is Llyn Brianne in Wales. Built in 1972, it has a capacity of 64.4 million cubic litres of water, covers a surface area of 2.3 square miles and plays an important role in supplying water for Wales.

Llyn Brianne feeds into the River Tywi, replenishing water abstracted further down the river at a treatment works near Carmathen. From this treatment works, the water is piped to the most populous areas of south Wales, including Neath, Swansea, and the west of Cardiff.

The reservoir’s claim to fame is that it is home to the tallest dam in the UK at a height of 91 metres. The dam is a popular tourist attraction when Llyn Brianne is spilling into the Tywi and a set of three hydroelectric turbines at its base can generate 4.60 megawatts of water.

Llyn Brianne’s big spillway has proven popular with kayakers in the past and in 2008 their activities in sliding down when water was released sparked media interest. Welsh Water, who are responsible for the reservoir, called the activity dangerous and said it had long been outlawed, even though the kayakers claimed to have been doing it for over 20 years.

Whilst humans may look forward to the release of water, it is not such good news for fish. The Tywi is home to important trout and salmon stocks. When the river is topped up by Llyn Brianne, the water tends to be very cold with anglers saying it adversely impacts on the quality of fish.

Llyn Celyn

If this were a list to find the most controversial reservoir in the UK rather than the largest, then Llyn Celyn in Wales would find itself at the top of tree. The Liverpool Corporation gained permission for the reservoir through a Private Act of Parliament in 1957, allowing them to bypass seeking consent from Welsh planning authorities.

Wales therefore had no say over the construction of a reservoir that would not even supply water for their region – instead, Llyn Celyn was for the people of Merseyside and the Wirral. To compound local anger, the village of Capel Celyn was to be flooded despite being a stronghold of Welsh culture and language.

The people of Capel Celyn marched through Liverpool in protest but it changed nothing. Their village destroyed to provide water for those in England. The construction of Llyn Celyn sparked a sharp increase in support for both the nationalist party Plaid Cymru and Welsh devolution. The City of Liverpool eventually apologised for constructing the reservoir… in 2005, just the 40 years after Llyn Celyn was opened in 1965.

In terms of numbers, Llyn Celyn holds 80.93 million cubic litres, making it the biggest reservoir in Wales. It covers a surface area of 2.05 square miles and pumps water into the River Tryweryn and the River Dee to make up for abstraction from further down the Dee.

The reservoir plays an important role in white-water rafting. When international events take place at Canolfan Tryweryn National White-Water Centre, Llyn Celyn releases additional water into the Tryweryn to improve conditions. There is a small hydroelectric power plant where the reservoir meets the Tryweryn to supply electricity to the national grid.

Haweswater Reservoir

Not quite as controversial as Llyn Celyn but definitely larger, the Haweswater Reservoir comes in at number three on our list of the biggest reservoirs in the UK. Just like our previous entrant, Haweswater was enabled by Parliament passing a Private Act. On this occasion, it gave the Manchester Corporation permission to raise the height of the original Haweswater Lake in the Mardale Valley.

Damming and flooding the valley created a reservoir capable of supplying water for Manchester and the north west of England. Opponents were aghast at the demolition of the centuries old Dun Bull Inn and the villages of Measand and Mardale Green to make way for the reservoir, which they said would alter the Lake District forever.

Construction took place between 1929 and 1935. Haweswater has a capacity of 84.84 million cubic litres, covers an area of 2.4 square miles and supplies around 25 percent of the north west’s water supply.

Between 1969 and 2015, Haweswater Reservoir was the only place in England home to a golden eagle. The lake has a population of schelly fish which are believed to have been present since the last ice age.

Although the reservoir has not been the disaster which many predicted, it remains a sensitive subject. Numerous non-fiction and fiction books have been devoted to Haweswater, including the winner of the 2003 Commonwealth Writer’s Prize for a first time book. Haweswater by Sarah Hall was set in Mardale at the time of the dam and the flooding of the valley.

Rutland Water

By surface area, Rutland Water is the biggest reservoir in the UK and one of the biggest in Europe. It has to settle for second spot on our list however as we are ranking the United Kingdom’s biggest reservoirs based on capacity – sorry Rutland!

Built in 1975, Rutland Water holds 124 million cubic litres over an area of 7.8 miles. It serves the city of Peterborough and the surrounding areas and was constructed by damming the Gwash Valley near Empingham.

Several villages were lost to the reservoir. Nether Hambleton and most of Middle Hambleton were demolished. The lower part of the church of Normanton was reinforced against water damage, enabling the building to survive and the upper part to tell the story of construction of the reservoir.

The parts of Middle Hambleton which remained are now considered to be part of one village with Upper Hambleton, known simply as Hambleton and found on a long peninsula which juts into the middle of the reservoir.

Rutland Water is more than a water source to the Anglian Water region; it also has great environmental importance. Large areas of wetland at the western end of the reservoir form a nature reserve, it is deemed is a biological site of special scientific interest and attracts birdwatchers from across the country. There is even a pleasure cruiser, the Rutland Belle, carrying people around the lake.

Kielder Water

And the winner… the largest reservoir in the UK by volume is Kielder Water, found in Northumberland. It holds 199 million cubic litres over a surface area of 6.74 miles and has a 27.5 mile shoreline.

Kielder Water was approved by the British Parliament in 1974 to increase supplies for the north east of England and its industrial economy which consumed huge amounts of water. The reservoir’s main role is to replenish the region’s rivers; it pumps directly into the River Tyne and is connected to the Wear and Tees via a water transfer scheme to compensate for supplies taken from those sources.

Underground springs feed Kielder Water and ensure it always remains at high levels. These springs coupled with the sheer size of the reservoir are the reason that the north east rarely has to implement drought measures.

A school, numerous farms and the permanent way of the disused Border Counties Railway were sacrificed for the reservoir. Work was completed in 1981, although it took another two years to fill Kielder Water because of its size.

As well as the biggest reservoir in the UK, Kielder Water is home to England’s largest hydroelectric plant. Opened in 1982, it generates electricity at the point where water is released into the Tyne. Kielder Water attracts more than 250,000 visitors a year, making it one of the region’s major tourist areas.


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