Water softeners remove mineral ions from your home’s water. These systems come in various sizes, with the size determining how many minerals are removed until regeneration needs to occur.

What Size Water Softener Do I Need?

It’s important to choose the proper size for your water softener. One that’s too small can:

  • Prematurely wear out its ability to soften water
  • Reduce the flow rate and pressure
  • Require more resources to maintain

One that’s too large can become an unnecessary expense. And, it can experience too few regeneration cycles, which can lead to significant damage.

It is critical to get the right size. It will save you money, time, and make your softener last longer. Check out these 5 steps for determining the proper size for your water softener.

How to determine the grain of hardness

To understand this initial step, it’s important to define what water hardness is.

What is Water Hardness?

Water hardness is measured by its calcium carbonate concentration. Water hardness is usually defined in terms of categories, ranging from “soft” to “very hard.” These classifications are calculated in:

  • Grains per gallon or gpg (this is the most common measurement form).
  • Milligrams per liter or mg/L.
  • Parts per million or ppm.

You may start with mg/L or ppm. To convert to gpg, just divide your measurement by 17.2.

How To Know What Level of Hardness You’re Dealing With

You shouldn’t guess or estimate your water’s hardness level. Try to get the most accurate reading possible to ensure your softener’s longevity. There are several ways to do this:

  • Test the water yourself. There are test kits available for purchase online, often for under $20. These let you test your water’s calcium levels and get a relatively accurate measurement from the comfort of home.
  • Get a report from a supply company. If you get your water from a local supplier, you can request a quality report for free. Past reports are also available online, or you can call your supplier directly for a more recent statement. It’s important to note that this option isn’t available to those who get their water from a private well.
  • Reach out to an independent laboratory. This is a great option, as an independent laboratory is neutral and won’t try to sell you unnecessary treatment options.

Watch Out For Iron

Elevated iron levels can influence the type of softener you get.

Your water may have higher than average iron levels if your water comes from a well.

For every 1 ppm of iron in your water, experts recommend adding 4 gpg to the total hardness level.

In some cases, you may want to add 4 gpg to the total hardness level for every 1 ppm of manganese.

What’s Your Water Consumption?

 Unlike the grain of hardness, it’s okay to roughly guess your daily water usage. This number will vary from day-to-day depending on your household’s:

  • Size
  • Cooking preferences
  • Hygiene habits
  • Attention to waste

If you want to leave little room for error, you can consult your household’s most recent water bill. This document will list your household’s water use within a specific time period, usually within the last month or year. Take this number and use it to find the average consumption on a day-to-day basis.

For example, if your bill lists your household’s consumption from the last month, divide the number by 30 to get the daily consumption.

If you don’t have easy access to a bill, you can get a rough estimate of your household’s water usage in gallons per day. Simply follow these guidelines:

  • The United States Geological Survey estimates that the average person uses between 80 to 100 gallons of water per day. Multiply the number of people in your house by a number in between 80-100.
  • Choose a number closer to 80 if you take short showers. If you’re less mindful of your consumption, choose a number closer to 100.
  • The number of people living in your home multiplied by the number you choose between 80 and 100 will give you an average number of gallons consumed daily.

Calculate Softening Requirement

Your softening requirement is the number of hardness grains your softener needs to eliminate every day. You can get this number by multiplying your hardness level (found in step 1) and your daily water usage (found in step 2).

Understanding Water Softener Capacity

Because of how the softening process works, a softener can only remove a limited number of hardness grains before it needs to be cleaned.

What is Regeneration?

When a water softener regenerates, it washes out and drains away built-up minerals.

Without regeneration, your softener’s resin beads wouldn’t be able to bind to any more magnesium or calcium ions. This could increase the hardness of your water and decrease its quality.

How Does Regeneration Relate to Softener Capacity?

All softeners must undergo regeneration to function properly. Experts suggest regenerating a softener every week. This can be controlled by your system’s valve. Regeneration is essential to maintain a good balance of:

  • Protection of the head valve
  • Low wastewater production
  • High softening efficiency

How to Calculate Softener Capacity

To calculate this measurement, multiply the daily softening requirement (found in step 3) by 7 days of the week.

This resulting number should give you the maximum number of grains that your product can soften in one week.

Consider Salt Efficiency (Also Known As Brine Efficiency)

While the number in step 4 is essential for understanding what size water softener to purchase, it should not be considered without taking salt efficiency into account.

When purchasing your softener, keep in mind that salt is needed to keep your softener working properly. You’ll need to add salt every two months or so, though you should check it monthly to ensure there’s a sufficient amount. Experts suggest using a nugget-style or clean pellet type of salt.

To completely regenerate a softener, you need a lot of salt. Partial regeneration allows you to get more use out of the salt you purchase. As you add more salt per dose, the efficiency per pound decreases.

It’s important to know your water’s total required grain capacity. This way, you can purchase a system that has a greater grain capacity. With a larger system, you can participate in partial regeneration. Partial, as opposed to complete, regeneration lets you. 

  • Save money on bags of salt
  • Service your system more efficiently
  • Lessen your negative environmental impact
  • Preserve the longevity of a sewage system (if your home has one)

Check For The Salt Rating

The salt efficiency should be listed on the model you purchase. The salt efficiency is almost always expressed as grains per pound. This number states how many grains of impurities the model can eliminate per pound. This number depends on the lowest possible salt dosage and takes real-life circumstances into account.

Choosing a Water Softener

Now that you’re aware of what must be considered when purchasing a softener, here’s how to go about choosing one.

Since you’ve made it this far, you should have figured out your home’s water usage and specific conditions. These figures allowed you to determine how much softening is needed daily.

Ideally, softeners are selected so that they only need to be regenerated once a week. The benefits of having regeneration occur only once a week include:

  • It keeps the resin bed in good condition.
  • It maintains the system valve’s durability.
  • It reduces water consumption. Depending on the system, the regeneration process may use up to 50 gallons of water. This can become excessive and wasteful if the system is set to regenerate more than once a week.

Let’s say you found your water softener capacity needs to be 21,000 hardness grains. Most retailers sell softeners that offer the following hardness grain capacities:

  • 24,000
  • 32,000
  • 48,000
  • 64,000

There are some deviations, but these are the standard sizes. Now, you may be tempted to think that a system with a grain capacity of 24,000 would be great for the above example. In theory, the 24,000 system will do its job and effectively soften your water.

However, it takes a significant amount of salt to completely regenerate this 24,000 system. If your softener needs to eliminate 21,000 hardness grains every week, the 32,000-grain system will save you a lot of money in the long run.

The larger system may cost more upfront, but you’ll want to make this leap. With a larger system, the bags of salt you purchase will last longer.

To sum this up, we recommend finding the number of hardness grains your softener will need to eliminate each week. Then, to figure out which system to get, go up one size.

Note: Often you’ll see the 24,000 system described as the “.75 cubic feet system”. Measuring water softeners in terms of cubic feet is an accurate way to describe these systems. The cubic feet represents the amount of resin in each system, which is needed to remove ions from your water.

Other Factors to Consider

 Here are a couple of factors to consider when making this purchase:

Flow Rate

 While weekly softening capacity is important, you must also take flow rate, measured in gallons per minute, into account. Your system needs to be able to deliver water efficiently during peak consumption times. If it doesn’t, hard water can leak through and cause a drop in pressure.

Larger homes tend to need higher flow rates of around 15gpm, while smaller families can get away with around 7gpm.

Commercial versus Home Softener

This guide is intended for those looking to purchase water softeners for their private residences. Commercial products have different configurations and sizing requirements. For advice on how to select a commercial water softener, we recommend reaching out to a local expert.

What Size Water Softener Do I Need for a Family of Three?

Let’s put some of what we learned into practice. Here, we’ll show you how to determine what size water softener to get for a family of three. Let’s assume the following:

  • This family sent a sample of their water to an independent laboratory and found their water hardness to be 12gpg.
  • This family is mindful of their water usage. Their usage per person is 80 gallons per day, so we’ll multiply 80 by 3 to get 240.
  • Their daily softening requirement is 12 multiplied by 240, which is 2,880. 2,880 times 7 is a weekly grain capacity of 20,160.

While the family could get away with a 24,000 system, they should get the 32,000 system. This system has more cubic feet of resin and will allow them to save money on salt.

Multi-Stage Water Filtering Media Technology Systems

The average homeowner may get a water softener and filter mixed up. They both work to improve the quality of your home’s water, but they’re designed with specific purposes in mind:

  • Softener: A softener has a more narrow focus, which is to remove minerals and reduce its hardness.
  • Filter: A filter is more broadly used to remove contaminants from your home’s water.

Both are designed to be whole-house systems. There are some multi-stage media technology systems that grant consumers the best of both worlds: softening and filtration in one system. The sizes of these systems will vary based on your home’s filtering and softening requirements.

After having your water tested, you may likely need a whole house filtration system. Depending on the quality of your water and what needs to be filtered out, you may need a specific system size.

If you invest in a larger filter size, you won’t need to service it as much. This can lower the cost of professional service visits or reduce the amount of time you spend on maintaining your system.

For this type of combination system, a 4.5″ x 20″ filter is customary. The lifetime you get from your filter will vary depending on the amount of sediment present in your water.

This type of dual system is ideal for those who want to ensure the highest quality of water possible. Just be sure to take your water quality, household size, and flow rate into account when determining what size filter to get.

Purchasing the Right-Sized Water Softener

Purchasing a water softener for your home can be a difficult decision. A lot of homeowners are unaware of the math and reasoning that goes into making a smart purchase decision. Hopefully, this guide has simplified the process of choosing the properly-sized water softener for your home.

For more information see our articles on how a water softener works, getting your home’s water tested, and this state website on how to size a water softener.

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Bob Olson

Owner - Operator at RT Olson Plumbing
Bob Olson has over 16 years experience in all aspects of residential and commercial plumbing. He's a 4th generation plumber. With over 200 five-star customer reviews, he runs one of the best-rated plumbing companies in Riverside, CA.
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