Determining the requirements for your new Water Softener

After you have decided to buy and install a Water softener for your home you will first need to decide the appropriate size you will need your softener to be.

To do this you will need to find out the level of hardness of your water supply and the requirements and consumption of your household.


The first thing to determine will be the level of hardness of your water supply. To do this you can either call your plumber or buy a water hardness testing kit and do it yourself.

Water hardness is measured in grains per gallon or GPG and once you run the test you will most likely obtain a figure of between 3 to 20 GPG, which is the range of hardness that can be found in the United States, although the average is of 10. Remember, 3 GPG is soft water and 20 GPG is extremely hard water.


The second thing to calculate is the amount of water consumed by your household, so you can determine too if it is a small, medium or large household.

Determining the daily water usage of your household is very simple: you will just need to take the amount of persons living in your house and multiply that figure by the average water consumption per person per day, which varies from 80 to 100 gallons.

But what number should you pick exactly? 80? 100? Or some number in between? You know your household better than anyone, so you will need to decide if the persons living there usually consume larger amounts of water or smaller amounts. If they tend to consume very large amounts of water every day then you can pick any figure from 90 to 100, if they tend to consume smaller amounts of water every day then you can pick 80 or 85. Remember it does not has to be an exact figure, a rough estimate will do.

So the formula would be:

Number of people living in your home x Water consumption of every person per day = Number of gallons consumed by your household every day


To calculate the weekly amount of water consumed by your household you will need to take the amount of water consumed daily and multiply it by 7.

So, for example, if you have a family of 5 and they tend to consume an average amount of water then the formula would be like this:

5 x 90 = 450

And the weekly amount would be of:

450 x 7 = 3150


The third figure you will need to determine is the amount of grains to be removed every week.

To calculate this you will need to multiply your household water consumption obtained above and multiply it by the amount of minerals that cause hardness (in GPG) which is the figure you obtained in the first step.

For example:

Using the amount of water consumption obtained in the example above which was of 3,150 and considering the level of hardness is of 10 GPG; then: 3,150 x 10 = 31,500

So, the amount of GPG that a softener would need to remove every week is of 31,500 GPG.


After this you will be able to choose the capacity of your water softener; they usually come in the following capacities:

  • 15,000
  • 24,000
  • 32,000
  • 40,000
  • 48,000
  • 64,000
  • 80,000
  • 100,000

Continuing with the example; the amount of GPG to be removed every week is of 31,500 GPG so a Water softener with a capacity of 40,000 would be the best option.


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