Finding ways to address water shortages during times of dry weather has constantly been an issue for water companies to solve.
As the mercury rises, demand can quickly outstrip supply, particularly in London where millions of people are crammed into a relatively small space.
These pictures, which were found during the recent office refurbishment at Coppermills water works, show the gruelling hard work carried out to lay the Thames to Lee Valley main.
After a period of dry weather, plus water shortages during the Second World War, the then Metropolitan Water Board decided the best way to ease supply and demand issues in East London was to build the new raw water main.
It was designed to carry raw, untreated water to reservoirs, which would then be treated to be suitable to drink.
The main, which is still in operation today, is a huge 112-inch in diameter, 19 miles in length and is buried up to 192 feet underground. It passes underneath some iconic London landmarks, including Paddington station and Lords Cricket Ground.
It took four years to build, between 1955 and 1959, and was officially opened in the autumn of 1960. During construction, miners dug out the tunnel for the pipe using pneumatic spades and drills, before sections of the pipe were transported down the tunnel on a train track.
They were then welded together in place, before a mortar lining was placed on the inside of the tunnel to reduce friction and prevent the pipe from bursting.
At the time of construction, it was quite a ground-breaking leap for the water board.
It was one of the first underground pipes it commissioned, as above surface pipes were previously preferred but drastic measures were being taken to keep demand up with London’s booming population, which then stood at 6.75 million. Today, it’s 8.8 million.