In today’s homes, most systems are either four stage or five stage systems, depending on the number of pre-filters involved. Water flow is driven by city water pressure starting at the first stage. The first stage consists of 5 micron sediment filter for removal of larger particulates. The second stage is a carbon pre-filter for removal of organic contaminants including chlorine and its by-products.

Next the water enters the reverse osmosis membrane, a very tight, sheet-like filter, that allows water to pass but rejects dissolved solids like sodium, calcium, metals and other impurities like lead and arsenic. Some of the water entering the unit is used to rinse the membrane surface and flows to the drain. The purified water is stored in a small storage tank until it is needed. When the faucet mounted at the sink is opened, the purified water from the tank is forced through another carbon filter enhanced with coconut shell for better flavor and taste, which gives it a final polish for before leaving the faucet.

(This is a simplified description of a four-stage RO systems.  Additional sediment and carbon pre-filters can be included. This simplified description omits a few very essential parts like flow control devices, check valves, and automatic shutoff devices that stops the inflow of water when the storage tank is full.)

Hard water is a common quality of water which contains dissolved compounds of calcium and magnesium and, sometimes, other divalent and trivalent metallic elements.

The term hardness was originally applied to waters that were hard to wash in, referring to the soap wasting properties of hard water. Hardness prevents soap from lathering by causing the development of an insoluble curdy precipitate in the water; hardness typically causes the buildup of hardness scale (such as seen in cooking pans).

Dissolved calcium and magnesium salts are primarily responsible for most scaling in pipes and water heaters and cause numerous problems in laundry, kitchen, and bath. Hardness is usually expressed in grains per gallon (or ppm) as calcium carbonate equivalent.

When water contains a significant amount of calcium and magnesium, it is called hard water.  Hard water is known to clog pipes and complicate soaps and detergents from dissolving in water. Water softening is a technique that serves the removal of the ions that cause the water to be hard, in most cases calcium and magnesium ions. Iron ions may also be removed during softening. This process is called ion exchange. Water softeners are specific ion exchangers that are designed to remove ions which are positively charged. Softeners remove calcium (Ca2+) and magnesium (Mg2+) ions. Calcium and magnesium are often referred to as hardness minerals.

A water softener collects hardness minerals within its conditioning tank and flushes them away by backwashing & regenerating the resin bed. This process will replace the calcium and magnesium ions in the water with other ions such as sodium (NaCL) or potassium (KCL) salts.

Water softening is an important process, because the hardness of water in households is removed. Water softening can prevent these negative effects. Water softening means expanding the life of household appliances, such as dishwashers, laundry machines, linens and clothing and extends the lifespan of  many other water-based applications.

There are cases to be noted, in which people with dry skin conditions have benefited from soft water. Hard minerals bond with soaps & detergents leaving an invisible film on hair and skin causing dryness. Depending on the hardness level of the water and a person’s skin sensitivity, Extremely hard water can cause skin to be red, itchy and irritated by some of the fragrances and perfumes found in many soaps today.