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
| Term | GPG* | PPM* |
| Soft | 1.0 or less | 17.0 or less |
| Slightly Hard | 1.0 to 3.5 | 17.1 to 60 |
| Moderately Hard | 3.5 to 7.0 | 60 to 120 |
| Hard | 7.0 to 10.5 | 120 to 180 |
| Very Hard | 10.5 or over | 180 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 Hardness | Your Number | Multiply By | Your Number | = | Compensated Hardness |
| 1 -20 | | 1.1 | | | |
| 21 – 40 | | 1.2 | | | |
| 41 – 70 | | 1.3 | | | |
| 71 – 100 | | 1.4 | | | |
| 101 – Plus | | 1.5 | | | |
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
