Mayfair is a district in the West End of London, in the City of Westminster. It is bordered on the north by Oxford Street, on the east by Regent Street, on the south by Piccadilly and on the west by Park Lane. It is one of the most exclusive and expensive residential areas in London and is home to some of the city‘s wealthiest people. The area has been a fashionable residential district for centuries, and has many well–known landmarks, such as Hyde Park, Buckingham Palace and Piccadilly Circus.

0 ppm is the softest water, 400 ppm is the hardest water. The level of calcium carbonate in this water zone is 269 ppm.

The water supplied to Mayfair is hard water.