What Size Water Softener Do I Need?

When it comes to buying a water softener for your home, size matters.

A water softener that’s too small won’t be able to handle the flow rate of your home’s water system, and could restrict water pressure.

A softener that’s too big may regenerate too infrequently and will cost more money upfront.

Ultimately, correctly sizing a water softener will help you to minimize salt and water usage in your quest to tackle hard water at home.

If you’re asking: “What size water softener do I need?”, or “how many grain water softener do I need?” this guide will provide you with all the information you need to correctly size a water softener for your household.

👉 Size your water softener in just a few clicks with my Quiz

📏 How to Size a Water Softener

To properly calculate the size of a water softener, you’ll need to know:

  • Your water hardness
  • Your average daily water usage

Water Hardness

Water with a particularly high hardness (a high level of calcium carbonate and magnesium) and excess iron will cause your softener to work harder to soften your water. 

If you live in an area with high water hardness and/or iron, you’ll want to look at a softener with a bigger grain capacity that can hold enough resin beads to effectively soften your water.

If your water doesn’t have very high levels of hardness, you can opt for a softener with a smaller grain capacity for your home.

Water hardness is measured in grains per gallon (GPG), parts per million (PPM), or milligrams per liter (mg/L).

You can measure water hardness with a hardness testing kit, which you can buy online.

HardnessGrains per Gallon (GPG)Parts per Million (PPM) & mg/L
Soft<1 0 – 17
Slightly Hard1.5 – 517 – 60
Moderately Hard3.5 – 7 60 – 120
Hard7 – 10120 – 180
Very Hard>10>180
water hardness scale

Water Consumption

When you size a water softener, you should know how much water you use per day, on average.

This means all the water you use, not only your drinking water usage.

Consider the number of people in your household, the number of appliances in your home, how often these appliances are used, and how this affects your water consumption.

If you’re on a municipal or city water supply, look at your water bill if you want an idea of your water consumption. It’ll tell you everything you need to know on how much water you use per month. You can then use this information to calculate an average of your water use per day.

If you’re using a higher volume of water per day – and don’t forget that your water-based appliances will have an impact on daily usage – you’ll need a water softener with a bigger capacity.

If your water use per day is lower, you’ll be fine with a water softener with a smaller capacity.

Calculating Your Water Softening Requirements

If, for whatever reason, you don’t have access to your water bill or you are on well water, you can calculate an average daily water consumption by multiplying the number of people in your household by 75.

For instance, you have a family of 3, you’ll need around 3 x 75 gallons (per person), or roughly 225 gallons of soft water per day.

When you know how much soft water you’ll need per day, you can ask yourself the next question:

How many grains do I need in a water softener?

Let’s say you’ve measured your water hardness with a testing kit, and you have 10 grains per gallon of water hardness. You know that your family of 3 uses about 225 gallons per day of water.

From here, multiply 225 (your average daily water consumption) by 10 (your water hardness) to find your water softening requirement – in this case, 2,250 grains of daily water hardness.

Because most ion exchange softeners are designed for once-weekly regeneration, the next step is to multiply your daily water softening requirement by 7 – for the 7 days of the week.

2,250 x 7 = 15,750. It’s never going to be an exact number, but you don’t need to look for a water softener with this exact grain capacity.

Most water softeners are available as 24,000 grains, 32,000 grains, 48,000 grains and 64,000 grains, so in this example, you’d round up to a softener with a 24,000 grain capacity.

To size water softener for your own household, use the following formula:

Average Daily Water Consumption x Water Hardness (grains per gallon) x 7 = Water Softener Capacity Requirement

🤔 Choosing a Softener to Meet Your Needs

Knowing how to size water softener is important not only for finding the right system for your needs, but also for ensuring your water softener works as efficiently as possible.

Capacity and efficiency are both big things to think about when deciding on which water softener is for you.

Water Softener Capacity

What does “grain capacity” actually mean?

A water softener’s capacity is a measure of the amount of hardness minerals it can eliminate from your water before regeneration is needed.

A single grain of hardness measures up to approximately 1/7000th of a pound of dissolved hardness minerals.

So, a water softener that has a 24,000 grain capacity can remove around 24,000 grains of hardness before regeneration.

You can use the calculation above to work out roughly how many grains of water hardness you use per week, and you can then match up your softening requirements with a water softener of the best softening capacity.

Water Softener Cost

The cost of a water softener depends on the brand, size, and features. The average water softener cost is $700-$2,200, but prices can be higher than this for particularly high-tech systems.

Don’t compromise on quality for the sake of affordability.

We recommend spending at least $1,000 on a water softener that has features that will help you to save costs in the long run, like metered regeneration and salt efficiency technology.

It’s best to look for a water softener with a built-in sediment water filter, too, that will protect the resin beads from abrasive contaminants. Sediment water filters are more important for well owners than for people with a municipal water supply.

Why Efficiency Matters

Some of the best water softeners are certified to NSF/ANSI 44, for efficiency.

According to NSF, efficient water softeners must meet minimum performance expectations for both salt and water.

Efficiency is calculated by comparing the amount of hardness removed from the water with the amount of salt and water needed for the regeneration process.

There are many things that can affect the efficiency of a water softener, including:

  • The salt dosage. Salt dosage determines the softening capacity of the resin bed. To some extent, increasing the salt dosage improves the exchange capacity. However, you will eventually reach a point where increasing the salt dosage will only minimally increase the exchange capacity. So, higher salt dosages are less efficient than low salt dosages.
  • The water softener’s regeneration mode. Using a water softener that regenerates based on a timer, rather than based on your water usage, will likely cause the softener to regenerate when it doesn’t need to, wasting salt in the resin tank.

So, why is water softener efficiency important?

The efficiency of a water softener dictates how much salt you need to buy, use, and release into the environment.

Considering the salt efficiency of a water softener when making a purchase should mean that your chosen water softener uses the least amount of salt as possible, but also never runs out of soft water.

This will reduce your maintenance requirements and keep your costs as low as possible throughout the water softener’s lifespan.

Related Content: Read our 2022 water softener system cost guide

Common Water Softener Sizes

What size water softener do you need – and what sizes are even available?

The most common system size is 32,000 grains, and most families do find that this is the ideal size for their softening needs, though you may opt for the next size up if your family members are a fan of long baths and showers.

The most common water softener sizes are as follows:

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

A 64,000 grain softener is typically for commercial use, though some large households do use them in their homes if their gallons per day of water consumption is particularly high.

You can also buy water softeners in two different styles: single-tank and dual-tank softeners.

The only real difference between the two is that single-tank softeners provide soft water on demand, while dual-tank softeners provide you with soft water whenever you need it. When one resin tank performs a regeneration cycle, the water softener simply uses the other resin tank.

🧑🏽‍⚖️ So, How Big of a Water Softener Do I Need?

Ultimately, deciding what size water softener is for you comes down to two things:

  1. The hardness of your water, and
  2. Your weekly water consumption

Neither of these figures are anything to guess at.

Find out what your water hardness is by using a testing kit. Your water bill will give you the best idea of how much water you use on average per day.

If you’ve found a water softener you like the look of, but you’re still not sure if it’s the right size for you, contact the manufacturer and explain your situation. A good manufacturer will guide you to make the right purchase for your needs.

🧠 How to Size Water Softener: FAQ

Can a water softening system be too big?

Yes, it’s possible to buy a softener that’s too big for your water’s hardness and your water usage. Avoid buying an oversized water softener.

Buying too big will mean that the unit can’t operate correctly as it’s designed for plumbing systems with a higher water pressure. The softener won’t regenerate enough, and if regeneration occurs too infrequently, bacteria may grow in the resin beads.

Plus, large tanks have a higher water and salt use, so buying the right size water softener will help you to use less salt and water in the system.

How much hardness is ideal?

After using a water softening system, your water hardness level should be 0-3 GPG (grains per gallon). As long as you accurately set your total hardness value in your water softener, it should remove virtually all the dissolved minerals in your water to achieve this optimal range.

What’s a good water softener size for a family of four?

A 32,000-grain ion exchange softener is best suited to a family of four. If your water usage is higher than average or you have extremely hard water, consider a 48,000-grain water softener instead.

Can you install a water softener yourself?

Yes, you can install a softening system yourself – as long as you’re a handy person. You’ll need to cut into your pipes and use a solder during the installation process. If you’re not confident in DIY, you may need to hire a plumber, who is guaranteed to do the job properly.