“The Journey to Soft Water”
As rain falls to the ground through Earth’s atmosphere, it often dissolves acidic gases from the air such as carbon dioxide and sulfur dioxide. When that water reaches the ground, the more acidity it has, the more soil it dissolves as it continues its journey. This gives our water both unneeded and unwanted minerals (total dissolved solids) as it is passes through our ground and surface waters (wells, springs, rivers, lakes, aquifers, oceans). Most of these substances are known as electrolytes, which dissolve in water to form electrically charged particles called ions.
You may have seen two of the most commonly occurring ions in natural water, at work–calcium and magnesium–by way of bath tub ring, shower door spotting, the “popping” of water heaters, dingy pots, pans, dishes and sinks to name a few. Because these two ions are positively charged, they are known as cations. While other cations are also present in our natural waters, such as sodium, iron, potassium and other metallic components, only calcium and magnesium make water hard, causing the problems mentioned above.
By enhancing nature’s process, modern technology can, by the common method known as sodium cycle operation, remove the calcium and magnesium ions and replace them in solution by using sodium. This process is known as positive ion exchange or cation exchange because the ions involved (magnesium and calcium) are positively charged. Negatively charged ions remain in the softened water, and softening does not reduced the total dissolved solids.
As the water begins its journey through the softening cycle, it encounters a bed of resin beads covered with soft sodium ions. The cation exchange material most often used is known as polystyrene resin, which resembles spheres or beads; this “sand-like” material is insoluble in water and has a negative electric charge. This is the site where the “exchange of ions” actually occurs. These beads are contained in a cylinder shaped fiberglass canister known as a resin tank. The untreated water enters this tank and
passes through the bed of resin. These negatively charged resin beads have a greater attraction for the two positive charges in each ion of magnesium and calcium than they do for the single positive charge of the sodium. Acting in the same manner in which a magnet attracts and holds a nail, these cation resin beads attract the positively charged ions of magnesium and calcium. Thus the resin beads will exchange the sodium ions for the “hard water” ions and allow “soft” water to flow from the resin tank. As long as there are plenty of sodium ions remaining on the resin beads, the softener will continue to produce soft water.
After processing a large number of magnesium and calcium ions, the resin beads will become saturated. So, before the regeneration process begins, the resin bed must be back washed whereby water is passed through the resin bed in the opposite direction of normal flow, flushing suspended matter out of the tank and down a waste water drain thereby loosening the beads of resin which were compacted as a result of the softening cycle. After the backwash cycle, the resin beads are soaked in a brine (a strong solution
of salt water) and then rinsed.
These ions force the magnesium and calcium ions off of the resin beads allowing them to be cleansed and ready for re-use. Your water has now completed its journey and is of soft water quality!
How often your water undergoes this journey as it enters your home depends on such factors as the size of your softener, your family’s water usage, and the hardness of the water in your home.