Reverse Osmosis, also known as hyperfiltration, is the finest filtration known. This process will allow the removal of particles as small as ions from a solution. Reverse osmosis is used to purify water and remove salts and other impurities in order to improve the color, taste or properties of the fluid. It can be used to purify fluids such as ethanol and glycol, which will pass through the reverse osmosis membrane, while rejecting other ions and contaminants from passing. The most common use for reverse osmosis is in purifying water. It is used to produce water that meets the most demanding specifications that are currently in place.

What is water softening?
     When water contains a significant amount of calcium and magnesium, it is called hard water. Hard water is known to clog pipes and to complicate soap and detergent 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.
     The best way to soften water is to use a water softener unit and connect it directly to the water supply.
 

What is a water softener?
      A water softener is an ion exchanger. 

1. Hard water--water with a high calcium/magnesium content--enters the softener through the "In" port indicated by the green arrow.  It passes through the control valve and into the tank, where it goes from top to bottom through a specially prepared resin that "softens" it.

2. The resin consists of specially manufactured beads that have been saturated with sodium ions.  "Softening" occurs as the hardness minerals in the water attach themselves to the resin and are "exchanged" for sodium.

3. The softened water then enters the long center tube, called a riser, via the strainer basket in the bottom of the tank and passes upward through the riser.  The water exits the softener via the control valve (blue arrow) and is sent to the home.

4. When the resin becomes saturated by hardness minerals, the softener automatically goes into regeneration. (The regeneration process is initiated by a timer or a meter, depending on the type of softener you purchase.) By this process the hardness minerals are washed down the drain (via a drain tube not shown in the diagram), and the resin bed is rinsed, resettled, and recharged with sodium.  It is now again ready to soften your water.

5. The regeneration process is accomplished by passing very salty water from the brine tank through the resin. 

6. The brine tank must remain filled with softener salt at all times so that it can regenerate the softening resin.