There’s no universal answer for this because the size of water softeners or the grain capacity (water softener capacity) largely depends on the size of the family or home, the water hardness, and the frequency of the regeneration process.

Average households may require water softener units with a 32,000-grain capacity or one cubic foot of resin. A large family will need more. The larger the family or occupants in a house, the larger the water softener capacity should be.

Another factor to consider is the degree of water hardness. The harder the water is, the larger the water softener capacity should be.

Aside from the water hardness level and the size of the household consuming the water, another factor to consider is the frequency of the regeneration process. Buying undersized water softeners will cause the system to regenerate twice weekly or thereabouts.

Then again, a suitably sized water softener should not take more than a couple of weeks before it initiates regeneration to prevent damaging the resin beads. This is the case when you go for an oversized water softener. For the ideal water softener capacity, regeneration occurs once a week.

There are several factors to consider when properly sizing your water softener. As you read on, you will know how to properly size a water softener, which includes using a softener sizing calculator.

Let’s begin by understanding the standard sizes.

Standard Sizes of a Water Softener

The grains of the hardness of a water softener system during one regeneration cycle indicates the capacity of that system. Alongside the capacity, also consider how much salt the softening unit uses. Therefore, to accurately size a water softener, you have to be familiar with the capacity produced by various quantities of resin beads.

This will help you identify the water softener unit with the best salt efficiency. The most popular sizes range between 15,000 to 80,000-grain capacity.

  • 0.75 cubic feet of salt equates to 15,000 grains
  • One cubic foot of salt equates to 20,000 grains
  • 1.5 cubic feet of salt equates to 30,000 grains
  • Two cubic feet of salt equates to 40,000 grains
  • Three cubic feet of salt equates to 60,000 grains
  • Four cubic feet of salt equates to 80,000 grains

Calculate Water Softeners Size

To size a water softener accurately, you’ll need to consider the water quality and the rate of water usage to arrive at the correct size. This will result in the maximum production of soft water and minimize salt use at the same time. These are the two key factors to consider to determine what size water softener you need.

You can start by measuring how much soft water you need daily (the quantity of water hardness you need to remove daily).

Measuring this involves factoring in the water consumption and water hardness.

Water Hardness

Water hardness is the amount of dissolved minerals such as calcium and magnesium dissolved in your water. It’s measured in milligrams per liter (Mg/L) and grains per gallon (GPG). Grains per gallon is the industry standard measurement unit.

This should be the first factor in measuring the size of a water softener. If the water softener is equipped with a digital programmer, you will have to input the water’s hardness value when programming.

You will need to conduct a water hardness test to know the total hardness value for well water. If you rely on municipal water supply, contact the local water utility regarding the water hardness value.

Daily Consumption

Water consumption refers to the quantity of water you consume every day through various activities such as cooking, drinking, bathing, laundry, etc. The quickest and most convenient way to measure your daily water consumption is by looking at your water bill. On your bill, you will see your monthly water consumption. Armed with this information, you can break the figure down to daily usage.

In the absence of a water bill, you can presume that an individual’s average daily water consumption is 75 gallons.

So for a family of 4, you’ll multiply 75 gallons by four which equates to 300 gallons of water daily. So this is how much water a family of four supposedly consumes in a day.

Calculation Example

The daily softening requirement for hard water measuring 10 grains per gallon will be 300 gallons x 10 GPG = 3000 grains of hardness daily. Since most water softeners initiate regeneration once every seven days, this will cause a balance between maintaining the freshness of resin beads, using less salt, and lessening wear and tear on the softener valves.

Since we’ve arrived at a daily softening requirement of 3,000 grains, the size of water softener you need will be 3,000 grains (daily requirement) x 7 days (regeneration frequency) = 21,000 grains.

When searching for this size in the market, you’ll notice that the most popular water softener sellers have 24,000, 32,000, 48,000, and 64,000-grains.

Since your house (in our example) requires a 21,000-grain capacity, you would think that 24,000-grains will fulfill your softening needs, but for a water softener to yield 24,000 grains, it will require a 27-pound bag of salt. Technically, this is undersized, so regeneration will occur more than once per 7 days, which means more salt will be used.

You’ll require roughly 36 pounds of salt for a 32,000-grain capacity. This size is better suited for your home because the 32,000-grain softener will be more salt-efficient and affordable for your family than the 24,000 grains in the long run.

In essence, a larger unit has better salt efficiency in the long run. So, now you should know how many grains you should be looking for.

water softener calculation and sizing chart

Water Pressure Flow Rates

For one cubic foot of salt, the water softener will soften hard water with a flow rate of roughly 5 gallons every minute. In a scenario where the water is moderately hard, which means a flow rate below 10 GPG, the water softener may handle a bit more than 5 grains every minute.

On the other hand, if the hardness levels exceed 30 grains per gallon, the softener may allow trace amounts of hardness ions to pass through at 5 gallons per minute for every cubic foot of resin.

Why Getting the Right Size Water Softener

Firstly, getting the right size water softener means you get to spend less on salt bags because the right sizes are more salt-efficient and affordable in the long run. From the salt deposits in the resin tank for the ion exchange process to the frequency of replacement and regeneration, you’ll use less salt.

Getting the right size water softener means that your water system will never stop producing soft drinking water while using minimal quantities of salt. All through the life cycle of this softening unit, you’ll discover the huge savings you’ve made thanks to less spending on salt bags.

About the Author

Diana Masson

Diana works as a saleswoman in a hardware store. She knows the smallest differences between the various water filter brands and knows exactly what her customers want. Diana is a mother of 3 children and has been a homeowner for 2 years. Her family can rely on having the purest drinking water because she had a water filter installed herself last summer. Which one? Ask her yourself :)

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