why does melbourne have such good drinking water
Water supply and sanitation in Australia Some 90% of Melbourne's drinking water comes from uninhabited mountain ash forests high up in the Yarra Ranges east of Melbourne. More than 157,000 hectares has been reserved for the primary purpose of harvesting water. These water supply catchments have been closed to the public for more than 100 years. Melbourne's water supply system is based on the principle that it is better to start with the highest quality source water than having to treat it to reach required standards. According to Melbourne Water, Melbourne is one of only about[weasel words] five cities in the world that has such protected catchments.[14] Water from the forests flows through streams in reservoirs, which provide security of supply for times of drought. One of these reservoirs is formed by the Thomson Dam on the Thomson River located about 130 km east of Melbourne in Gippsland, from where water flows through a 19 km long tunnel through the Great Dividing Range into the Upper Yarra Reservoir and then onto Silvan Reservoir for distribution as drinking water in Melbourne. In recent years, drought has resulted in depletion of much of the water in the reservoir of the Thomson Dam.
Fresh water Out of all the water on Earth, saline water in oceans, seas and saline groundwater make up about 97% of it. Only 2.5–2.75% is fresh water, including 1.75–2% frozen in glaciers, ice and snow, 0.5–0.75% as fresh groundwater and soil moisture, and less than 0.01% of it as surface water in lakes, swamps and rivers.[5][6] Freshwater lakes contain about 87% of this fresh surface water, including 29% in the African Great Lakes, 22% in Lake Baikal in Russia, 21% in the North American Great Lakes, and 14% in other lakes. Swamps have most of the balance with only a small amount in rivers, most notably the Amazon River. The atmosphere contains 0.04% water.[7] In areas with no fresh water on the ground surface, fresh water derived from precipitation may, because of its lower density, overlie saline ground water in lenses or layers. Most of the world's fresh water is frozen in ice sheets. Many areas suffer from lack of distribution of fresh water, such as deserts.