How To Size A Water Softener?

Water softeners benefit nearly all households, especially throughout the United States, where 85% of water is hard. A water softener works to remove minerals such as calcium and magnesium from the water through a process called ion exchange.

Water without these minerals is referred to as “soft”. It can be more beneficial for various uses, such as reducing mineral buildup on plumbing fixtures or protecting the life of dishwashers, washing machines, and other laundry appliances. As essential household appliances, properly sizing a water softener is critical to ensure you get the right system.

However, how to size a water softener? That depends on your family member and how much water they spend. To calculate the appropriate water softener size for your household, multiply the daily water consumption per person (usually 80 gallons) by the number of individuals in your home.

Then, multiply that figure by the grains of hardness in your water to determine the number of grains that need to be eliminated daily. Let’s discuss this in more detail.

Things That Influence Water Softer Size

Knowing how big of a water softener do I need is a struggle; several factors should be considered. The size of the water softener that is best suited for any given application depends on the hardness of the water, the daily water usage, and the material is softened.

Hardness: The hardness of the water determines how much calcium and magnesium need to be removed to soften the water. This is usually measured in grains per gallon (mpg).

Daily Water Usage: On average, the amount of water your family uses determines how much water needs to be softened. Typically, this is calculated by multiplying the number of people in your household by 80 gallons daily, but remember that individual household habits can vary significantly from this estimated value.

Material Being Softened: The type of water being softened also plays an important role in determining the size of the water softener. For example, if you have a well, you may require a larger system to handle higher iron levels and other minerals. On the other hand, if you are on city water with lower amounts of hardness than average, then a smaller system might suffice.

Once you have determined the size of the water softener your household requires, you can begin shopping around. Consider all available options and compare features such as salt capacity, grain capacity, and regeneration frequency.

Salt-based systems are more affordable in the long run than ion exchange systems as they require less frequent regeneration. However, an ion exchange system can be a better option if you want a low-maintenance system that doesn’t require salt.

How to Size A Water Softener?

In order to use the water softener calculator, it is necessary to have both the hardness number and the consumption amount in gallons. The calculation involves multiplying the hardness number by the daily gallons.

If there are four individuals consuming 320 gallons of water and the hardness level is 8, the total amount would be 2,560 grains. As a result, your water softener would need to eliminate 2,560 grains daily.

The equation for determining the grains to be removed per day is the product of the hardness value and the total gallons per day.

The calculation of 8 grains per gallon multiplied by 320 gallons equals 2,560 grains per day.

To adjust for high iron levels in your water, add 3 grains per gallon (mpg) for every 1 milligram of iron, then proceed with your calculations. If this process seems overwhelming, utilize a simple water softener sizing calculator.

What Problems It Will Cause if I Buy Undersized Water Softener?

Determining what size water softener do I need is never an easy task. And many people make mistakes by taking undersized. If you’ve recently installed an undersized water softener, it might fail to produce enough soft water for your household. This means hard water will go through your plumbing instead, beyond a certain usage level, or if too many faucets run simultaneously. Doing so negates all the fabulous water-softening benefits you expected – making this problem all the more frustrating.

Moreover, a unit that is too small will require more frequent regeneration to flush out built-up minerals in the resin beads; this should ideally occur as needed. In modern systems, this is done based on demand – whereupon the greater number of particles in the beads triggers the regeneration process. Choosing a system with the right size capacity for your needs is vital.

What Problems It Will Cause If I Buy an Oversized Water Softener?

Having an oversized water softener can come with its own set of problems. When buying one, it’s important to understand the capacity figures provided by the manufacturer. Otherwise, you won’t be able to accurately estimate salt usage, particularly considering that regeneration will occur less frequently than with an undersized unit.

This will mean more money spent upfront for the softener. However, you may end up using less salt and water during each regeneration cycle as a result of this.

Another factor to consider when buying an oversized water softener is how much it will cost in terms of energy use and supply costs. Considering this long-term is important so they don’t take a toll on your budget later.

Unfortunately, the benefits of having an oversized system — like reducing salt usage — can often be overshadowed by the cons if not saving on energy is considered before purchase.

Frequently Asked Questions [FAQs]

1. Can You Have Too Big Of A Water Softener?

Yes, you can have too big of a water softener for your home. Typically, the size of water softener you should choose depends on the amount of water your household uses and the hardness of the water in your area. If you purchase a water softener that is too big for your household’s needs, it can lead to over-softening and over -regeneration, which can be costly and inefficient.

2. How Do I Know What Size Water Softener To Buy?

The best way to determine the size of the water softener you need is to use an online sizing calculator. These calculators consider your home’s water hardness, household size, and estimated daily water usage to estimate the size of water softener that is best for your needs.

3. Does Water Softener Size Matter?

When it comes to water softeners, size does matter. The size of your water softener is determined by a few factors, including the hardness of your water, the amount of water you use each day, and the number of people in your household.

4. Can You Drink Softened Water?

Yes, you can drink softened water. Water softeners are designed to remove hard minerals such as calcium and magnesium from the water supply, which may otherwise build up on fixtures and appliances over time. Softened water is generally safe to drink and use for cooking, but it’s important to size a water softener correctly to ensure that the right amount of salt is used in the softening process.

5. Is Soft Water Healthier?

Soft water results from softening, removing magnesium and calcium from hard water. The result is “softer” water that feels slippery and soapy. While it may be beneficial for use in bathing, laundry, and cleaning dishes, there is no scientific evidence that soft water is healthier than hard water for drinking or cooking.


It is important to correctly size your water softener to ensure you’re getting the most out of your system. An improperly sized water softener can lead to over-softening, over-regeneration, and higher energy costs. Before purchasing a water softener, consider your home’s water hardness, household size, and estimated daily water usage when using an online sizing calculator to determine the size of the water softener that is best for your needs.

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