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Water Hardness

Softening Requirements
Page 4

This softening-regeneration cycle can be repeated almost indefinitely, over many years of service in the home. Most modern water softeners use either a timer or a sensing system to automatically initiate the regeneration process. A separate brine tank holds the salt for multiple regenerations and dissolves the salt for use as needed. Thus the homeowner need only add salt to the brine tank periodically to insure a constant supply of softened water.

Water softener capacities are given in terms of the number of grains of hardness they will remove between successive regenerations. The number of gallons softened between regenerations is calculated by dividing the rated capacity (in grains) by the number of grains of hardness in one gallon of water. The following table shows how this works out.

Hardness of Water Supply in Grains per Gallon (gpg)Rated Capacity of Softener in Grains of Hardness Removed
 10,00020,00030,000
5200040006000
10100020003000
1566713332000
2050010001500
30333667100
50200400600

Gallons of Water Softened Between Regenerations

An average family uses about 70 gallons per person per day for all water uses in the home, or about 50 gallons per person per day if hard water can be supplied to toilets. In selecting a softener for a home, it is usually recommended that it has enough capacity to last at least three days between regenerations. The following example shows how these various factors can be used.

Let us assume that we have a family of four persons, the water has 20 grains per gallon of hardness, and all the water is to be softened. We can then figure:

4 persons x 70 gallons per day x 20 grains per gallon x 3 days equals 16,800 grains minimum softener capacity

A second factor to be considered is the peak flow rate required in the home. The following table and graph (see next page) can be used to estimate the peak flow in a home, based on the various fixtures which are to be supplied with softened water, assuming all were being used at the same time.

Guidelines for estimating Flow Rate Requirements

The estimated flow rate requirements for plumbing fixtures used intermittently on a water supply line may be obtained by multiplying the number of each kind of fixture supplied through that supply line by its weight from the above table, adding the products, and the referring to the appropriate curve with this sum. (See the Flow Rate/Fixture Unit Graph on next page).

Finally, any softener selected should carry the Gold Seal of the Water Quality Association. It is your assurance that the equipment has been tested against rigid voluntary industry performance standards, has successfully passed these tests, and has been Validated by the Water Quality Association. This Association is an industry organization of equipment manufacturers, suppliers and dealers in the industry, and is dedicated to public education in the field of water quality.

IMPORTANT: The determination of which treatment method is best should be made only after careful consideration of many factors such as economics, water quality characteristics, the end use to which water is to be put, temperature variances of the water to be treated, the inherent limitations of the available treatment technology, and others. This determination can best be made by your local water treatment representatives and they should be consulted prior to the purchase and installation of any water treatment equipment.

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