Calculate your hardness:

Either in PPM (Parts Per Million) or in GPG (Grains Per Gallon)
• If you have PPM convert by dividing by 17.1
• If you have GPG convert by multiplying by 17.1
Until you have reached your grain hardness

First Determine if a softener is needed, see defined chart below.

Terms Defined

TermGPG*PPM*
Soft1.0 or less17.0 or less
Slightly Hard1.0 to 3.517.1 to 60
Moderately Hard3.5 to 7.060 to 120
Hard7.0 to 10.5120 to 180
Very Hard10.5 or over180 or over

* GPG -Grains Per Gallon

**PPM – Parts Per Million

Compensated hardness:
When sizing water-conditioning equipment, the hardness should be based on compensated hardness. Compensated hardness takes into consideration minerals and other factors that will reduce the softening capacity of a softener. These items cannot be picked up in a standard hardness test. To arrive at compensated hardness,
multiply the figure on the right by the hardness in grains per gallon.

Note: Always Determine both (1) FLOW RATE and (2) CAPACITY total in grains

Your Test HardnessYour NumberMultiply ByYour Number=Compensated Hardness
1 -201.1
21 – 401.2
41 – 701.3
71 – 1001.4
101 – Plus1.5

Flow Rates in Pipes

3/4″=10-15 GPM
1″=16-30 GPM
1-1/4″=30-35 GPM
1-1/2″=40-70 GPM
2″=65-120 GPM
2-1/2″=80-170 GPM
3″=120-270 GPM
4″=250-500 GPM
6″=500-1100 GPM
8″=1000-2000 GPM
10″=1500-3000 GPM

Number of People using softened water in household

Number of people using softened water in household