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Water softening terms

By Water Quality Association (WQA)

The following water softening terms are explained courtesy of the Water Quality Association (WQA).


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Water Softener

“A compound which, when introduced into water used for cleaning or washing, will counteract the effects of the hard water minerals (calcium and magnesium) and produce the effect of softened water. For example, detergent additives and polyphosphates.”

“A pressurized water treatment device in which hard water is passed through a bed of cation exchange media (either inorganic or synthetic organic) for the purpose of exchanging calcium and magnesium ions for sodium or potassium ions, thus producing a softened water which is more desirable for laundering, bathing, and dishwashing. This cation exchange process was originally called zeolite water softening or the Permutit Process. Most modern water softeners use a sulfonated bead form of styrene/divinylbenzene (DVB) cation resin.”

Water Conditioning

“The treatment or processing of water, by any means, to modify, enhance, or improve its quality or to meet a specific water quality need, desire, or set of standards.”

In this context, a water conditioner means a device that conditions the water to your preference. It can be a water softener and sometimes refers to a specific kind of water softener that doesn’t use salt. It can also refer to a water filter combination unit or simply a nonspecific water treatment unit.

What other terms do I need to know to select a water softener?

Grains per Gallon (gpg)

“A common method of reporting water analysis results in the United States and Canada. One grain per gallon equals 17.1 parts per million (ppm) [of minerals] or 17.1 milligrams per liter. Grains per Imperial gallon equals 14.3 mg/L (or ppm).”

Rated Capacity


“As relates to softening or ion exchange, rated capacity, as stated by the manufacturer, may refer to any of several figures, all of which are given in relation to the period between regenerations:

1. the expected number of days the equipment will be in service;

2. the expected number of gallons of product water delivered; or

3. the grains of total hardness removed.

The capacity of an ion exchange system will vary, within limits, with the amount of regenerant used.

In filtration or adsorption applications, the manufacturer\'s statement regarding the expected number of days the equipment will be in service or the expected number of gallons of product water delivered before it is expected that backwashing and rinse down should occur.”

Most water softeners feature a rating capacity that reflects how many grains of total hardness is removed, i.e., 20,000 gpg; 30,000 gpg, etc.

Regeneration Level

“The quantity of regenerant, usually expressed in pounds per cubic foot of ion exchanger bed or pounds per regeneration, used in the regeneration cycle of an ion exchange system. Regeneration level may also be called salt dosage.”

Salt Efficiency

“In an ion exchange water softener, the hardness removal capacity calculated as grains of hardness removed divided by the weight of salt in pounds that is used to achieve that amount of hardness reduction. Operational salt efficiency refers to the salt efficiency performance of a water softener under conditions of actual or simulated long term use (six months or more) in a household where gallons of water usage typically varies from day to day.”

Different kinds of salt can have various efficiencies. Evaporated salt has the highest efficiency, followed by solar salt and rock salt.



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Water softening terms:  Created on October 6th, 2012.  Last Modified on October 9th, 2012


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