Water softeners operate on the ion exchange principle, a process in which water passes through an ion exchange medium. The most common softener uses a "salt-based medium” of resin beads that are coated with sodium or potassium ions.  As the untreated water passes through the resin, divalent cations like calcium, magnesium, iron, manganese, radium, barium, strontium, copper, lead, and zinc are exchanged for the monovalent (single positive charge) sodium or potassium cations . The multivalent cations (multiple positive charges) are more strongly attracted to the negative charges of the resin beads and displace the sodium or potassium cations which are released into the water. 

If the unit is properly designed the system will automatically backwash itself and recharge the resin by passing a sodium or potassium brine solution across the resin. During this process, the opposite exchange occurs and the divalent or multivalent cations are removed from the resin and replaced by sodium or potassium cations. This is possible because even though the divalent cations are more strongly attracted to the resin, they are swamped and crowded out by the very high concentration of the monovalent cations in the backwash process. These systems are typically designed based on the anticipated peak and average water demand, number of users, total number of fixtures, and the total hardness, pH, alkalinity, iron, hardness, and manganese content of the water.

Because the overall water quality of your drinking water and resins are susceptible to poor performance because of the presence of bacteria, sediment, highly oxidizing solutions, metals that leave coatings, salts, and chlorine, it is critical that a comprehensive informational water test is conducted (Level 3) and that you complete a Diagnostic Analysis of your water (Level 1) to determine if there are other contaminants, like bacteria, sediments, and salts, that may be impacting your water quality.

It is important to note that “salt-based systems” can significantly elevate the sodium levels of the treated water which could be a problem for those with high blood pressure. There are a number of "salt-free systems" that use a chemical to sequester the divalent cations, especially iron and manganese, that add to the hardness of the water. These sequestering chemicals do not remove the divalent cations, but combine with them so as to keep them in solution. These chemicals tend to work best when the issues related to hardness are moderate. The NuvoH20 uses a citric-acid-based sequestering agent and the Aquios unit uses a polyphosphate additive known as Siliphos as a sequestering agent. For these systems, it is typically necessary to conduct a rather comprehensive water quality test, so we recommend conducting one of the Level 3 testing packages listed below in the recommended tests section.

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Follow the Path to Clean Water

We recommend that, prior to installing a CounterTop POU (Point-of-Use) Unit, you Get Informed by gathering as much information as possible and Get Tested by conducting multiple levels of testing depending on your needs: Level 1 Observational Testing using our Self Test Web App, Level 2 Do-It-Yourself Testing, Level 3 Informational Lab Testing and, if needed, Level 4 Certified Testing conducted by a water professional.

If you have any questions please Contact the KnowYourH2O team.