What if I told you that beneath this calm surface lies a story of engineering ingenuity and London’s thirst? Welcome to the Queen Elizabeth II Reservoir. This reservoir is more than just a body of water. It’s a vital part of London’s water supply. It holds over 19 million litres which equates to 10% of the raw water storage for London. Once treated it provides clean water for millions across Surrey and London.
The Queen Elizabeth II Reservoir’s story began in 1935. The Metropolitan Water Board authorised its construction. Jonathan Davidson was the chief engineer. Work started in 1936. However, the outbreak of World War II in 1939 halted progress. Construction recommenced in 1957. W and C French undertook the project. Finally, in 1962, the reservoir was completed. Queen Elizabeth II formally opened it on March 30, 1962.
Look closely at the embankment walls. They stand 15 metres above the ground. The perimeter stretches for 4400 metres. The walls have a rolled clay core. This core extends into the blue London clay below. The clay core is 3.6 metres wide at the base. It tapers to 3 metres wide at the top. Mixed clay and gravel fill both sides of the core. This fill is 0.9 metres wide. Gravel was dragged from the reservoir floor to construct the walls.
The inlet and outlet valve towers sit at the northeast and northwest corners. Tunnels run beneath nearby reservoirs, roads, and houses. They lead to the Walton Water Treatment Works. The inlet tunnel is 1035 metres long. The outlet tunnel is 795 metres long. These tunnels are vital arteries in London’s water network.
Let’s talk about water quality. The Queen Elizabeth II Reservoir plays a role in improving it. The water quality changes during reservoir storage. The reservoir helps to reduce ammoniacal nitrogen. It also helps to reduce albumin nitrogen. This is done through natural processes.
Did you know that the Queen Elizabeth II Reservoir is an important habitat? Bewick’s swans have been spotted here. Back in 1963, 100,000 gulls roosted at the reservoir. Little auks and red-necked phalaropes have also made appearances. The reservoir’s design affects the fish population. Concrete shores limit breeding to European perch and ruffe. Empty fish cages with netting support some plant growth. This allows small numbers of other fish to breed.
Now, look out onto the water. Notice anything unusual? In 2016, Thames Water commissioned a floating solar farm here. It was the world’s largest at the time. Over 23000 panels cover one-tenth of the reservoir’s surface. This solar farm generates 6.3 MW of power. That’s enough to power approximately 1800 homes. It also offsets Thames Water’s energy expenses.
In 2021, significant work was undertaken to guarantee the integrity of the inlet and outlet transfer tunnels. Barhale was engaged by Thames Water as principal designer and principal contractor to complete the tunnel relining contract. The goal of the project was to increase resilience by strengthening the Wedgeblock tunnels. The inlet tunnel is 1060m in length and the outlet tunnel is 826m in length.
So, the Queen Elizabeth II Reservoir stands as a testament to engineering. It highlights ecological importance and renewable energy. It’s a place where London’s history and future flow together. Next time you turn on the tap, remember the journey. Remember the Queen Elizabeth II Reservoir. Remember the story of the water reaching your glass.