There are maintenance costs, because the RO membrane needs replacing according to the manufacturer's recommended schedule. The cost of a unit needs to be weighed against the type and quantity of contaminants in the water and the concern for safety. Further, compare the cost of an RO unit to other alternatives, such as bottled water. Water Softeners Hardness minerals in water can have a large effect on the home. Hard water is caused by dissolved calcium and magnesium in the water.
Hard water interferes with laundering, washing dishes, bathing, and personal grooming.
It also affects appliances. For example, scale builds up in water heaters, increasing the costs of heating water and reducing the life of the appliance. Hard water, when used with soap, causes soap deposits that will not dissolve. Water is softened by passing through a bed of ion-exchange resin. The softening process exchanges calcium and magnesium ions in the water for sodium ions in the resin.