Sodium Ion Exchange Water Softeners

• The most common and cost-effective solution for hard water is the sodium-ion exchange, or salt-type water softener. These softeners replace magnesium and calcium ions with sodium ions. The sodium ion water does not damage plumbing or water heaters, and it does not leave stains as untreated hard water might. These systems treat large volumes of water in a cost-effective way. However, these systems do not purify, disinfect or otherwise treat the water. By replacing calcium and magnesium ions with sodium, this form of treatment may prove a health risk to individuals with sodium restrictive diets.
  
  

Salt-free Softeners

• The most common salt-free alternative to the standard water softener uses a potassium-ion exchange instead of a sodium-ion exchange. This method delivers similar volumes of softened water without adding sodium. Potassium salts are roughly four-times as expensive as standard sodium softeners.
  
  

Filtration Softening

• The most common form of filtration softening in the home is the reverse-osmosis (RO) system. This system screens out dissolved calcium and magnesium as well as biological contaminants. This is a one-step purification as well as a softening system. RO systems discharge roughly 15 times as much water as waste as they deliver purified water. RO systems are more expensive to install and require filter changes on a regular basis while delivering a fraction of the volume of softened water seen with ion exchange systems.
  
  

Distillation Softening

• Heating your source water to release pure water vapor, then cooling the vapor and collecting the pure condensate is the water distillation process. Like the RO filtration, this process both softens and purifies the water. It is also more expensive to set up and has a high operating and maintenance cost; likewise, it delivers less water per dollar than the ion exchange softeners. Unlike the RO system, there are solar methods of water distillation which may produce household quantities of drinking and cooking water.
  
  

Magnetic Water Softeners

• There are a number of magnetic water softening systems on the market. Some use permanent magnets and others use electromagnets. Both types claim to change or re-align hard water contaminants to reduce or eliminate the effects of hard water without changing its chemical nature. Conflicting data on the results of magnetic water softening leave this method in the "unproven" category.