甚麼地區使用硬水及軟水..urgent

The hardness of the water depends on the calcium and magnesium ion content in the water. More calcium and magnesium content means higher hardness. If the water is mainly from the spring or underground or lake, due to the minerals from the ground, the water usually contains higher calcium and magnesium content, the water is therefore harder. If the region uses the water from rain or from melted ice, since the water has less contact with minerals, the mineral content is lower and the hardness is lower. For example, in HK, the source of water is from rain and river in which the water is from the ice in Mountain Himalaya. So, teh water is softer. However, in Europe, teh main source of water is from the underground water, due to the presence of minerals, the water is therefore harder.

硬水是含有鈣Ca2+，鎂Mg2+離子的水，例如洗衣服之類，由於硬水會與清潔劑形成浮渣(scum)而嚴重降低清潔效果。
1.甚麼地區使用硬水,為什麼?
在沒有軟水可以使用的地方，例如使用河水和井水的地方。
2.甚麼地區使用軟水,為什麼?
在城市，因為有濾水廠去進行處理，在硬水中除去鈣Ca2+，鎂Mg2+離子，使水變成軟水。