Not every drop of water that comes out of the tap is the same depending on where you live.
For example, if you live in Tidworth, a town that was rated to have the tastiest water and second-softest water in the country, your water will taste very different to that found in the Isles of Scilly or in Bristol.
Part of the reason for this is that water often travels a very long way to reach your tap, either through pipes or through rock deposits. During that time the water may take small amounts of calcium, magnesium and other minerals along with it, forming what is known as hard water.
How bad hard water actually is depends on what you use the water for. If you primarily just drink it, that added calcium and magnesium can provide some health benefits, much in the same way eating a banana can.
In some industries, such as brewing, water can be deliberately hardened as part of the industrial process. The process, known as Burtonisation and named after the town famous for its mineral water, is claimed to bring out the flavour of hops in beer making.
However, in a lot of industrial and domestic processes, hard water can be somewhat of a menace and may necessitate the use of a block salt softener to artificially reduce the water hardness.
Hard water does not allow soaps to produce lather, instead creating soap scum that can lead to flat, lifeless hair.
More troubling than this is that calcium deposits can form limescale deposits on taps, in the middle of kettles and in plumbing pipes which can over time clog plumbing and cause boiler failures and broken pipes.
As a result, industries that use a lot of water need to be careful to monitor water levels to avoid broken boilers, cooling towers and systems that rely on regular water flow.