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Cation Exchange Water Softeners

WaterSense Products Pipeline

WaterSense Products SearchCation exchange water softeners remove the calcium and magnesium ions found in hard water by exchanging them with sodium (or potassium) ions. Once all the ions are fully exchanged, the water softener undergoes a regeneration process to flush the system of excess ions and recharge with new sodium ions.

Why a Specification?

The process of regeneration can use 25 gallons of water or more per day, or up to 10,000 gallons per year. Recent improvements in water softening technology, however, have reduced this water consumption and demonstrated that there is great potential for water savings. WaterSense believes there is an opportunity to capitalize on this water savings opportunity, raise consumer awareness, and further improve the efficiency of water softeners.

Notice of Intent

In November 2010, WaterSense issued a notice of intent (NOI) to develop a draft specification for water-efficient, high-performing cation exchange water softeners. The NOI outlines the efficiency and performance criteria WaterSense is working to define and the technical issues that still need to be resolved related to this product category.

On January 19, 2011, EPA held a public meeting to address questions regarding the NOI and gather input from stakeholders for specification development. For more information, please review the following documents:


WaterSense is not proceeding with the development of a draft specification for water softeners because it needs to further explore the concerns raised by some stakeholders in regards to the effect of water softener discharge on wastewater treatment. WaterSense is encouraging all interested parties to provide input on any of the issues presented in the NOI and will inform stakeholders if the program decides to move forward with a specification in the future. If you have comments or suggestions on the cation exchange water softener specification development process, please contact us at