The Ultimate Guide to Choosing What Size of Water Softener to Buy

If you are looking for a new water softener for your home, there are several things to consider in order to make the best decision.

One of these is determining the proper size water softener for you.

Many people think that the larger the complex water system, the better,  but this could be far from the truth.  

Luckily, this article will go over all of these factors and give you some questions to consider in determining what size of water treatment system you will need at your residence.

But, what exactly does a water softener do?

The water softener system makes hard, mineral filled-water into soft water and clean drinking water.

Water has minerals like magnesium ions, which we call “hardness.”

This hardness can lead to soap scum buildup essential and dull skin and hair.

Some regions have naturally occurring harder water than other regions;  so it’s important to know the level of hardness your water supply has.

A lower number means there are fewer minerals in the water or softer water. A higher number means more minerals in the water,  which means more challenging water.

In a Hurry?

When it comes to determining the best size for your softener, there are three key factors to consider:

1. How many people live in your home, and what are the daily hard water usage requirements are.

This will help determine how much water is being used each day, which will help you decide which size of water softening unit you need.

2. Quality of water that goes into the system will affect the regeneration process and time required.

Generally speaking,  the harder the water, the more often requires a regeneration cycle (or recharge).

This also requires a larger unit.

3. Consumption habits include how often people use hot water or take long showers/baths.

This will determine how much resin beads, or softening media you might need,  to prevent scaling build-up from happening at a faster rate than usual.

Factors in Determining What Size of Water Softener You Need for Your Home

1. How many available spaces in square feet do you have?

  • The first thing is to know what type and what size of water treatment system is required to assess your square footage available.
  • A standard rule of thumb that most professionals go by is; for every 400 square feet of space, you will have about 1 cubic foot of resin.  
  • Take this amount and multiply it by your desired flow rate (gallons per minute).
  • Then, divide that number by 60 (minutes in an hour). This will give you the size system required at your home.

2. How many people live in the house?

  • The number of people in the house is vital because larger homes use more water and therefore require a more extensive system.
  • If there’s just one person in the house, a typical 50-100 grain capacity will work fine for him.
  • If several people live in the house, then it may be worthwhile to have a 200-250 grain capacity system. 

Everyone can enjoy soft water without adding up to their water bill.

3. What is the hardness level of your water?

Find out what water hardness level per gallon of water is in the water supply in your area.

Once you know the hardness level of your water, you will then know how much salt, and how much water, or your daily water usage your softener will need to regenerate.

If you’re on city supply, then the hardness of your water or your grain of hardness will be at an average for most cities which is around 220-250 ppm (mg/L).

If it’s less than 200 ppm (mg/L), then you’re in good shape with almost any size softener system, unless, of course, if more people are living in your house.

So you really have to determine your daily water consumption or the amount of water used by your household.

If you have hard water between 200-300 ppm (mg/L), however, we recommend that you get a system with about 50 lbs. with the amount of resin capacity.

This is to make sure that you have enough water softening for everyone who lives there,  even if they use a lot of appliances and water.

If you have more than 300 ppm (mg/L), I’d recommend that you get a system with at least 100 lbs. of resin capacity.

The harder the water is,  the more time it takes to soften it.

4. Determine the Flow Rate

The flow rate is the speed at which the water pressure is out into the beads, and you need to know what size of equipment is required.

The higher the flow rate, the larger the system that will be required.

If you have a minimal equipment unit, it won’t take the minerals out of the water fast enough.

On the other hand, if you have a large equipment unit, it will eventually “cycle” off.

Instead of regenerating completely, as it should, it will do so partway through its cycle. It can cause white mineral deposits on appliances in your home.

Due to overuse, it will also damage the resin bed inside your system.

You’ll also use a lot of salt, so it is also important to know the salt efficiency, and it indicates how much pounds of salt was used or the amount of salt your household consumes.

If you have hard water from the city water supply, if your flow rate is reasonable, and if you don’t use too much salt, then the size of your resin would be less.  

It would have low hardness levels but with high flow rates.

5. Know your daily softening requirement

Your average daily usage will depend on the number of family members.  It is essential to know how much water an average person uses or consumes.

But, do not forget to include cooking, laundry, bathing, etc. in this calculation. These activities can contribute to an increase in the number of minerals dissolved in your water.

Say, for example,  if you have two people at home who use 40 gallons of hard water per day, you will need about two cubic feet of resin.

If your daily softening requirement is below 20 gallons per day, you should use less than four cubic feet of resin capacity.


Q: How do you know if you need a water softener?

A: Test your water quality. The easiest way is to get a FREE Water Test from Culligan.

If your test reveals that you have hard water, which is likely, there are a few more questions to ask yourself to determine the right size water softener for your home.

You should also check the ppm of iron in your water to determine if it has only 0.3mg of iron or less, as recommended by EPA.

Q:   What is “grain capacity”?

A: The grain capacity of your water softener is the measurement used to determine how much hardness it can remove before needing regeneration.

The higher the grain capacity, the longer it will go between regenerations, and the less salt will be added to your water.

Q: Do I need a plumber to install a water softener system?

A:  A water softener system can be installed by an experienced DIYer or a plumber.

It’s easy to install a water softener system, but it’s imperative to consult the manufacturer’s instructions beforehand.

When it comes to water softeners, one size does not fit all.

While many people believe that bigger is always better when reverse osmosis systems, this isn’t necessarily true when it comes to sizing.

A little research upfront can go a long way in ensuring that you get what you need without having too much,  or purchasing something too small,  for your needs.

If you’re still unsure how large a water softener you will need, the best next step is to talk to a professional.

They can take all of these factors into consideration, provide additional information specific to your home, and give you the necessary guidance on what best water softener size you need.

We hope this article helps you determine what size of water softener you need to purchase for your home.

Have any questions? Or do you have any tips or tricks to share? Please leave them in the comment section below.

D. Hahn

DIY guru, dad, husband, blogger. When I'm not creating life hacks I'm teaching my kids how to fix stuff after their dad breaks it.

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