Rivers, lakes, streams, wells and oceans all have in varying degrees some or the other sort of contaminants. The contaminants can be dissolved solids or minerals. The total amount of dissolved solids present in the water is called the salts in water. Salts in water can be broken down into positively and negatively charged ions. Anions are negatively charged while positively charged ions are called Cations. Positively charged ions of minerals like iron, magnesium and calcium cause the hardness of water. It is this hardness of water that causes scaling of pipes, boiler coils and formation of scales in utensils and other metal objects that come in contact with water for prolonged periods of time.
Water softeners convert the hard water into soft water by a process called ion exchange. Sodium and potassium ions present in the water softeners exchange places with these ions and make the water soft. All this happens due to the presence of resin beds that are present in the water softener. The resin beds have either sodium chloride or potassium chloride. When the resin bed is exhausted of most of its sodium or potassium chloride then the process of regeneration begins. It is also during this time that the water softeners loose their effectiveness.
In a commercial water softener, generally used for large residential or commercial complexes, water flows from the source into a tank and travels down towards the collector. As it travels down it passes over a resin bed where the ion exchange takes place and sodium or potassium ions replace the calcium, iron or magnesium ions. This water is now soft and then passes via pipes and valves into households.
The second step is called the backwash cycle. In this the water rushes into the tank through the valves and thoroughly rinses the resin bed and then rises and passes down the drain.
In the next step brine or salt is drawn into the valve of the softener from the brine tank. The brine flows down the tank and collects all the hardness ions that are present on the resin bed. This continues till the brine tank is empty of all brine. After this step the slow rinse cycle begins and the excess brine and hardness ions are rinsed out of the tank. This is followed by another cycle called as the fast rinse cycle. In this cycle water flows at faster rate and compacts the resin bed and removes any residual hardness ions.
The last step is the refill cycle. In this water flows into the brine tank and salt is dissolved in the proportion of 3 pounds of salt per gallon of water. This is the last cycle and the softener returns to its service cycle.