Generally, water filtration systems are not needed in Scotland as long as the water is sourced direct from the mains potable supply. Water filtration systems are useful in two circumstances. The first is areas with hard water where limescale leaves a layer of mineral deposits, and the second is when travelling outdoors and drinking freshwater from a natural source such as a spring. In the second instance, it is recommended to purchase a portable water bottle with a replaceable carbon filter such as this one from Amazon.