Instructions for Computing Water Softener Size/Capacity

You will need a water analysis to complete this.

If you feel this method is too complicated, use our line by line Worksheet Method that follows this, instead. (It's much longer but more foolproof.)

First, find out your water"s Total Hardness in GPG: Total Hardness (in ppm) divided 17.1 =Total Hardness in GPG. For example San Antonio = approx. 18 Grains.

Then, Adjust for Iron: Add 4 grain Hardness per 1 ppm of Iron detected (round up). For example, San Antonio = 139.0 ppb = 0.139 ppm x 4 = .278 extra Grains, so round up to 1 Grain.

Then, Adjust for Manganese: Add 4 grain Hardness for per 1 ppm of Manganese detected (round up) For example, San Antonio = 2 ppm x 4 = 8 extra Grains

This tells you the ADJUSTED TOTAL HARDNESS. Write it Here:_________Grains

1) Multiply (number of people in house) x 80 – 100 gallons (hot climates, pools, can use more water) to determine Household Daily Average Use (Gal.).

2) Multiply this (Household Daily Average Use Gal.) x ( ADJUSTED TOTAL HARDNESS)

3) Multiply this number by the (number of days Desired between regeneration cycles). Maximum days is 3 days.

4) This is the minimum softener capacity (in Grains) needed to handle your average household water demand.

Insider Tip from the manufacturing engineers: Use the Minimum Hardness Capacity (MHC)of a softener (not the maximum capacity) to gain a 40% salt savings advantage.

Typical Mineral Tank Sizes and Typical Minimum Hardness Capacity (MHC):
9x48” Tank = 1 cubic foot=Typ. MHC: 20,000 Grains=Max. Capacity: 30,000 GPR
10x54 Tank = 1.5 cu.ft.=MHC: 30,000 Grains=Max. Capacity: 45,000 GCR
12x52 Tank = 2 cu.ft.=MHC: 40,000 Grains=Max. Capacity: 60,000 GCR
14x65 Tank = 3 cu.ft.= MHC: 60,000 Grains=Max. Capacity: 90,000 GCR
16x65 Tank = 4 cu.ft.=MHC: 90,000=Max. Capcity: 120,000 GPR
21x62 Tank = 7 cu.ft.=MHC: 140,000=Typ.Max. Capacity: 210,000 GPR

*GCR = Grains Capacity until next Regeneration

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Long Worksheet for Choosing a Water Softener Size/Capacity

These are engineering calculations, so grab your calculator, pen, and print this out. Just take your time and double check your work when finished. (This is for standard water softeners softeners that use salt.

Your will first need to find out what is your:

Total Hardness (ppm, GPG, or Grains)
Iron (ppm or ppb)
Manganese (ppm, if available)

Get this from your municipal water supply authority or from a water analysis of your private well water. You cannot proceed without this important info.
*to convert ppb to ppm simply move the decimal point 3 positions to the left. So for example 139.0 ppb = 0.139 ppm

Insider Tip from the manufacturing engineers: You choose a water softener size according to it's Minimum Capacity (NOT the maximum capacity) in order to gain a 40% salt savings advantage. When you push a water softener to it's maximum capacity, it ends up wasting (and discharging) a LOT of salt.

First, find your water's Total Hardness in Grains:
(Total Hardness in ppm) divided by 17.1 = Total Hardness in GPG. (Grains Per Gallon)
This info would come from your local water provide or a water analysis.
Write answer on Line A:______Grains of Total Hardness (GPG)

Adjust for Iron: Add 4 grains Hardness per 1 ppm of Iron detected (round up)
For example (for S.A.) 139 ppb = .139 ppm* x 4 = .556 extra Grains = 1 extra Grain (when rounded up) This info would come from your local water provider or a water analysis.
Write Answer on Line B:______extra Grains due to Iron

Adjust for Manganese: Add 4 grains Hardness for every1 ppm of Manganese detected (round up) [So (for S.A.) 2 ppm x 4 = 8 extra Grains] This info would come from your local water provider or a water analysis. (Use 1 grain if info is unavailable.)
Write Answer on Line C:______ extra Grains due to Manganese.

Calculation: Add Lines A+B+C to get your ADJUSTED TOTAL HARDNESS.
Write answer here on Line D:_____Grains Adjusted Total Hardness.

Write the number of people using water in the house
Write answer here on Line E: ______people using water in the house

Estimate how much water each person uses per day using only these numbers provided:
Typical average average US consumption= 80 gallons (per person per day)
We are maybe a little above average consumption = 90 gallons
We are definitely above average, swimming pool, hot tub, watering, etc. = 100 (or more) gallons
Write the answer here on Line F:_____Gallons per Person per Day

Calculation: Multiply Line E x Line F to determine Household Daily Average Use (Gal.)
Write your answer here on Line G:_____Gallons

Calculation: Multiply Line G x Line D:
Write your answer here on Line H:______

You can have your softener regenerate every 2, 3, or 4 days. Choose one of these numbers and write your answer here on Line I:_____days between regeneration cycles. Remember each regeneration cycle consumes water and salt.

Calculation: Multiply Line H x Line I
Write your FINAL ANSWER here on Line J:____________Minimum Softener Capacity.

This is the Minimum Softener Capacity (in Grains) needed to handle your average household water demand and experience a maximum efficiency in salt consumption and minimize your salt discharge to the drain.

Finally, Match the value on Line J to a Minimum Capacity on the table below.

Now select your softener according to the Maximum Capacity that corresponds to the Minimum Capacity. For example, if your calculations show you that you need a MHC of 35,00 Grains, then round up to the MHC 40,000 Grains size, and then notice that it has a corresponding Max. Capacity of 60,000 Grains. Buy a 60,000 Grain Max. Capacity Unit.

Typical Mineral Tank Sizes and Typical Minimum Hardness Capacity (MHC):
9x48” Tank = 1 cubic foot=Typ. MHC: 20,000 Grains=Max. Capacity: 30,000 GPR
10x54 Tank = 1.5 cu.ft.=MHC: 30,000 Grains=Max. Capacity: 45,000 GCR
12x52 Tank = 2 cu.ft.=MHC: 40,000 Grains=Max. Capacity: 60,000 GCR
14x65 Tank = 3 cu.ft.= MHC: 60,000 Grains=Max. Capacity: 90,000 GCR
16x65 Tank = 4 cu.ft.= MHC: 90,000 Grains=Max. Capacity: 120,000 GCR
21x62 Tank = 7 cu.ft.=MHC: 140,000 Grains=Max. Capacity: 210,000 GCR

*GCR = Grains Capacity until next Regeneration.

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