There are many different types of conditioners, each with its own benefits.
The method used most often in homes is cation exchange, the principles of which are simple. An ion is an electrically charged atom or group of atoms. A cation is a positively charged ion. The water is conditioned when the hardness ions (magnesium and calcium) are exchanged for sodium ions. This exchange occurs in a resin bed during the softening cycle.
Three main parts make up most water conditioners:
- Resin Tank – Contains the resin bed.
- Resin Bed – This is made up of tiny bead-like material often made of styrene and divinylbenzene. The beads attract and hold positively charged ions such as sodium, but will exchange them whenever the bead encounters another positively charged ion such as calcium or magnesium.
- Brine Tank – This tank holds the dissolved salt solution that is necessary to regenerate the resin. Regeneration refers to reversing the ion exchange operation. The magnesium and calcium ions are driven off of the resin beads and replaced by positively charged sodium ions. The regeneration occurs when the resin beads are washed with a strong salt-water solution. The salt forces the calcium and magnesium ions to be released, and they are then discharged as waste during the backwashing cycle. The beads are ready to once again attract hardness ions from the water.
Many installed water conditioners are fully automatic.
An automatic unit regenerates according to a preset clock. For example, it might be set to regenerate every third night at 3am. Other systems may use an electronic sensor that regenerates the system according to water usage.
Size and Type Considerations
When water conditioners were first manufactured, manual and semi-automatic models, where the homeowner started the regeneration process “manually”, were the most common types sold.
Today, the two main types on the market are automatic and demand-initiated regeneration (DIR) water conditioners.
Automatic conditioners regenerate on a schedule regulated by a timer. DIR conditioners are the most sophisticated, containing a hardness sensor or water meter which triggers regeneration as needed.
There are several factors that a person must take into consideration before purchasing a conditioner, including the number of people in the home, how much water is used, and the hardness of the water.
Determining the size of the conditioner, knowing these factors, is rather simple. Multiply 75 (average gallons per day used per person) by the number of people in your household. For example, four people in a household will likely use 300 gallons of water per day. Multiply the 300 gallons per day by the number of grains per gallon of hardness present in your water. Continuing the example, 300 gallons per day times 20 gpg gives a figure of 6000 grains of hardness per day that would require removal. Given a typical regeneration capacity of 18.000 to 30,000 grains per regeneration, a softening system in this case would optimally be regenerated every three to five days.
The Sodium Issue
For some consumers, the fact that sodium is used to soften water raises a concern about their drinking water and a potential health risk. However, what many people may not know is that when doctors and researchers discuss salt and its effects on a person’s health, they usually refer to sodium chloride, and not sodium bicarbonate, which is the result of softening.
Further, according to Dr. Andrew Zeifer, Director of the Hypertension Clinic at the University of Michigan, “Drinking water represents a very small part of sodium intake in most persons. Even water softening systems using salt don’t introduce enough salt to be of concern.” Similar views were expressed in the New England Journal of Medicine, and by the U.S. Environmental Protection Agency.
If consumers do not want to add any additional sodium to their diet, or if they are on a medically prescribed diet, they may choose to connect their water conditioner to the hot water line only, thus leaving consumers able to drink and cook with unconditioned cold water. Another option would be to install a reverse osmosis or distillation system, and have the full benefits of both technologies in their home.