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Optional Water Efficiency Measure: May contribute to the 30 percent water efficiency requirement,
depending on the chosen WaterSense® Approved Certification Method (WACM),

UNDERSTAND
Water softeners are common household
appliances found in regions where hard water (or
water that contains higher amounts of dissolved
calcium or magnesium) is prevalent. Hard water
can cause scale to form on the inside of pipes,
water heaters, and other appliances and
equipment. Scale does not conduct heat well and
can reduce the flow of water through pipes and
fixtures. Hard water also reacts with soap to form a
sticky coating on skin and reduces soap's ability to
lather, which can make a bath, shower, or clothes
washer cycle less productive.
Cation exchange water softeners remove the
calcium and magnesium ions found in hard water
by exchanging them with sodium (or potassium)
ions in salts that include chloride. Once all the
ions are fully exchanged, the water softener
undergoes a regeneration process to flush the
system of excess ions so that the system is again
ready to soften incoming hard water.
Water softeners are not necessary in all homes.
They should only be considered in areas of
substantial hardness or where recommended by
appliance manufacturers, local health and safety
codes, and/or water utilities. Some jurisdictions
may limit the use of water softeners or have
requirements that must be met to minimize water
waste or preserve water quality.
The NSF/ANSI 44 Residential Cation Exchange
Water Softeners standard includes a voluntary
efficiency rating that requires softeners to use 5.0
gallons of water or less per 1,000 grains of
hardness removed.
Water softeners that use demand-initiated
regeneration are more efficient than water
softeners that function based on a fixed schedule.
Not Just Water Efficiency
When selecting a water softener to install in a
home, it's best to consider not just water
efficiency, but salt efficiency too. Salt efficiency
defines the hardness removal capacity of a water
softener and is measured in grains of hardness
removed per pound of salt.
Salt efficiency is important for two reasons. First,
greater salt efficiency reduces the amount of salt
that needs to be purchased and supplied to the
unit by the homeowner. Second, it decreases the
amount of sodium and chloride ions that are
discharged into the home's wastewater. Too
great a concentration of these ions can negatively
impact septic systems or affect the ability for the
community to meet water quality discharge limits
for sodium and chloride or reuse municipally
treated wastewater.

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ITI BUILD
•	AVOID installing water softeners when
water hardness levels do not indicate a
need for softening.
•	SPECIFY demand-initiated regeneration
systems that meet the voluntary
efficiency rating requirements of
NSF/ANSI 44. Select models with a
lower water consumption (i.e., gallons
per 1,000 grains of hardness removed)
and higher salt efficiency (i.e., grains of
hardness exchanged per pound of salt).
•	CONSIDER supplying softened water
only to a subset of fixtures or household
uses. For example, consider plumbing
the system to only soften hot water.
Likewise, outdoor water use, for
example, may not require softened
water. Reducing the demand on a water
softener will result in lower water
consumption and operating costs.
^=| VERIFY
•	OBTAIN the make and model number
for all water softeners.
•	REVIEW the manufacturer's product
specification sheet or product literature
to determine water efficiency and salt
efficiency.
Alternatives to Water Softeners
Technologies have been developed that provide alternatives
to traditional cation exchange treatment. Evidence suggests
that some of these devices can provide anti-scaling
treatment without the use of salt and reduce water
consumption from flushing the system. The links below
provide information on some of the alternatives.
•	University of Nebraska Extension Fact Sheet:
https://water.unl.edu/article/drinking-water-
wells/salt-free-water-softener-alternatives
•	City of Waterloo, Ontario, Information on Softener
Alternatives: https://watersoftenerfacts.ca/how-
softeners-work/#alternate
IAPMO/ANSI Z601 Standards for Scale Reduction Devices
was developed to evaluate whether softening devices or
other treatment devices effectively reduce scale. More
information about the standard can be found at
www.wqpmag.com/services/product-testing-
certification/article/10958980/testing-for-scale.
Learn More
Visit WaterSense's Cation Exchange Water Softeners web
page at www.epa.gov/watersense/cation-exchange-water-
softeners for more information.
*NOTE: Consult with the Home Certification Organization for specific verification protocols.
This technical fact sheet is part of EPA's Technical Reference Manual for
WaterSense Labeled Homes. For the full document and other tools and
resources for homes, visit www.epa.gov/watersense/tools-and-resource;
EPA-832-F-23-016

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