Westminster is a borough of London, England, located to the west of the City of London. It is home to some of the most iconic landmarks in the city, including the Houses of Parliament, Big Ben, and Westminster Abbey. The borough is also home to a number of other important institutions, such as Buckingham Palace, 10 Downing Street, and the Supreme Court. Westminster is a popular tourist destination, and its central location makes it an ideal base for exploring the rest of London.

0 ppm is the softest water, 400 ppm is the hardest water. The level of calcium carbonate in this water zone is 271 ppm.

The water supplied to Westminster is hard water.