Enter the water hardness, softener capacity, number of people in the household, and average water usage into the calculator to determine the salt usage for your water softener per month.

Water Softener Salt Usage Formula

The following formula is used to calculate the salt usage for a water softener.

SU = (H * U * P * 30 / C) * 8

Variables:

  • SU is the salt usage (pounds per month)
  • H is the water hardness (grains per gallon)
  • U is the average water usage (gallons per person per day)
  • P is the number of people in the household
  • C is the softener capacity (grains)

To calculate the salt usage for a water softener, multiply the daily grain removal (water hardness times average water usage times number of people) by 30 days, divide by the softener capacity, and then multiply by the average salt usage per regeneration (typically 8 pounds).

What is Water Softener Salt Usage?

Water softener salt usage is the amount of salt a water softening system uses to remove minerals from hard water. The system works by exchanging the minerals for sodium ions in a process called ion exchange. The amount of salt required depends on the water hardness, the capacity of the softener, and the water usage of the household.

How to Calculate Water Softener Salt Usage?

The following steps outline how to calculate the salt usage for a water softener.

  1. First, determine the water hardness (H) in grains per gallon.
  2. Next, determine the average water usage (U) in gallons per person per day.
  3. Next, determine the number of people in the household (P).
  4. Next, determine the softener capacity (C) in grains.
  5. Next, gather the formula from above = SU = (H * U * P * 30 / C) * 8.
  6. Finally, calculate the salt usage (SU) in pounds per month.
  7. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Water hardness (H) = 15 grains per gallon

Average water usage (U) = 75 gallons per person per day

Number of people in the household (P) = 4

Softener capacity (C) = 30,000 grains