Public water fountains are to be installed at Guy's Hospital near London Bridge and St Thomas' Hospital close to Westminster Bridge as part of a new network of fountains and bottle refill points promoted by Mayor of London Sadiq Khan.
St Thomas' Hospital already has a drinking fountain near the main entrance which uses paper cones.
Now new fountains are to be installed at both of SE1's main NHS hospitals as part of a new network of 20 refill points around the capital.
Mayor of London Sadiq Khan said: "Water fountains are a simple but effective way to encourage Londoners and visitors to ditch plastic bottles and instead refill reusable ones.
"With the hot weather we've seen this summer, the demand is greater than ever for quick and easy ways of accessing free drinking water and I'm pleased to confirm the locations for the first 20 of our new public water fountains.
"Some of these are already attracting thousands of visitors a day and City Hall are working on plans to secure many more across London."
The Mayor also supports Refill London, which has so far recruited over 2,000 London shops, businesses, venues and cafes including Costa, Tate Modern, BFI IMAX and Leon to provide free tap water to members of the public and isa partnership between City to Sea, Mayor of London and Thames Water.