What if My Water Softener is Too Big (Oversized)?

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It’s an unfortunate problem to have: You buy a new water softener for your home, only to discover that it’s too big for your needs.

We’re not talking about the actual size dimensions of a water softener, here (although that could also be an issue if your installation space is limited). We’re talking about buying a water softener with a capacity that’s too big for your water pressure and household size.

In this guide, we’ve shared what we know about oversized water softener systems, including their potential setbacks and dangers.

📌 Key Takeaways

  • An oversized water softener is a softening system with a higher capacity than you need, designed for higher water pressure than you have.
  • Oversized water softeners cost more money and may waste more salt and water than correctly sized softeners.

📐 What Is An Oversized Water Softener?

When we say a water softener is oversized, we’re not referring to the softener’s physical size, but to its softening capacity.

👨‍🔧 Water softeners are measured in capacity by grains per gallon, or GPG. An oversized water softener is a system that has a higher grains per gallon capacity than you need, based on your household size and water hardness.

The bigger a softener’s grain capacity, the more salt can be stored in the brine tank and the greater the salt capacity in the resin beads. Large water softeners can go longer between regeneration cycles – but this isn’t always a good thing.

Water softener installed in small space

⛔️ Setbacks Of Buying A Water Softener That’s Too Big

You might think that in the water softening market, the bigger, the better. After all, you want a tank that’s large enough to deal with all the hard minerals in your water, and you’d rather have a system that’s slightly too big than have to deal with low water pressure and slow water flow caused by undersizing a softener.

While this is true, oversizing a water softener as a precautionary measure against poor water flow is not the solution. In fact, water softeners that are too big have their own potential setbacks:


Buying a water softener that’s too big for your home means you’re needlessly spending extra money for no additional benefits.

An average-sized water softener with a capacity of 40,000 grains per gallon (GPG) costs about half the price of a large, 80,000 grains per gallon (GPG) softener designed for homes with 7-8 people.

You could end up spending upwards of $3,000 for an oversized water softener when you could buy the same unit in a smaller model for around $1,500.

Grain Capacity Average Price Range
20,000 - 24,000$600 - $1,000
30,000 - 32,000$600 - $1,500
40,000 - 48,000$1,000 - $2,000
60,000 - 64,000$1,500 - $2,200
70,000 - 80,000$1,800 - $3,200+

Water Flow Rate

You might think that installing an oversized water softening system will only do good things for the pressure and flow rate of your water supply, but this isn’t true.

A bigger water softener tank contains more resin beads. This extra volume of water softener resin requires a higher incoming water pressure, so there’s enough force to send water through the entire resin bed without significantly reducing flow rate.

👨‍🔧 If your home’s water pressure is too low for the water softener, there won’t be enough force to send water quickly through the resin beads. As a result, the water leaving the softener will have a greatly reduced flow rate.

Plus, a larger water softener needs a higher water pressure to regenerate. If your pressure isn’t adequate, the softener might not be able to send brine solution into the resin tank at a fast enough rate, reducing the concentration of the brine and affecting the efficiency of the sodium replenishing process.

Another issue is that when the rinsing stage of regeneration occurs, the softener might still be drawing brine into the mineral tank, so the brine isn’t completely drained once the regeneration process finishes.

Low water pressure

Infrequent Regenerations

Most modern water softener systems regenerate based on the volume of water that flows through the system. Once a certain volume has been reached, and the resin beads have only around 25% sodium left, the system will automatically regenerate.

The problem here is that buying an oversized softening system will result in regenerations that are too infrequent.

The water softener resin needs to be flushed at least once every 1-2 weeks, both for hygiene purposes (to prevent bacteria buildup, for instance) and to keep the resin beads working properly in the ion exchange process.

You might think you’re winning if you buy a large water softener that only needs to regenerate once a month – you’re saving money by using less salt and water, after all.

But if the water softener resin isn’t flushed often enough, there’s a risk that you might permanently damage the system.

This is especially the case if you have a well water supply that contains a lot of iron alongside dissolved minerals. Water softeners treating iron need to regenerate frequently to prevent a buildup of damaging iron minerals in the softener resin.

Iron Fouling

Iron and manganese are two minerals that are commonly found in well water supplies. These minerals foul water softener resin, even if they’re present only in trace amounts in a water supply.

The longer iron and manganese are adhered to the resin beads without being flushed away, the higher the likelihood of long-lasting damage to the resin.

So, if you have a softener that’s too big for your water usage or water hardness, the softener won’t regenerate often enough to flush away the minerals before they cause permanent fouling.

For that reason, it’s actually better to buy a properly-sized soft water system that performs more frequent regeneration cycles if your drinking water contains iron and manganese. This will maximize the system’s performance in the long run by extending the resin’s lifespan.

Water softener ion exchange resin

Day Override

Some demand-initiated water softeners (those that regenerate based on the volume of water flowing through the system) have a feature called “day override”, which programs the softener to regenerate after X amount of days, regardless of how much salt remains in the resin.

This means that the resin is flushed as necessary, even if, for example, you were on vacation and your water consumption was at zero.

If you oversize a water softener with a “day override” feature, the softener will probably end up regenerating based on this “day override” schedule (which is usually about once every 7 days) rather than actually regenerating once a certain volume of water is used.

Why? Because you’re not using water at a fast enough rate for the softener to regenerate based on volume, so the softener takes matters into its own hands.

This is exactly what you don’t want when it comes to system efficiency. It means you might still have 30%, 40%, or even 50% sodium ions still in the resin when the software initiates a “day override” regeneration, and all this sodium will end up being wasted when the system backwashes.

As a result, you’ll end up using more salt in your softener because up to half of it will get wasted when the system regenerates based on the “day override” setting.

Demand initiated water softener regeneration setup


Channeling is another risk of installing a soft water system that’s too big for your home.

Channeling is when water repeatedly flows through the resin bed in the same path, rather than through the whole bed, and typically occurs when your water flow rate is too low for the softener’s grain capacity.

As a result, only a small amount of resin in the softener is used and regenerated, which means that this section of resin becomes worn out before the rest of the resin.

💡 What’s the problem with this? The used section of resin will stop softening water at a much faster rate than if the whole resin was being used, meaning that you might end up with hard water when you shouldn’t in between system regenerations.

Plus, you’ll probably have to replace the resin earlier than expected because the single section of used resin loses its sodium-holding abilities while the rest of the resin is virtually untouched.

Hard water causes dry and itchy skin

🤔 Are Oversized Water Softeners More Efficient?

No. Oversized water softeners are only slightly more efficient than correctly-sized softeners, but nowhere near efficient enough to justify the extra cost.

On average, 1 pound of salt removes 2,400 grains of calcium and magnesium minerals in a water softener.

This is true in a softener of any size, whether it’s 20,000, 30,000, or 40,000 grains.

So the softener will use the same amount of salt to soften your water regardless of its size. The only difference is that a larger softener will go longer between regenerations, which will reduce salt wasted during the regeneration process – but leaving too much time between each regeneration cycle has its own risks and setbacks.

📦 When Should You Buy A Big Water Softener?

So, oversizing a water softener might do more harm than good – but in what instances should you buy a big water softener with a high grain capacity?

There are three key reasons to buy a big water softener:

  1. You have extremely hard water (a high amount of calcium carbonate minerals)
  2. You have a large home and need a large volume of softened water per day
  3. You want to minimize water softener regenerations (safely – any water softener still needs to regenerate once every 1-2 weeks)

📝 Most manufacturers offer at least two or three softener sizes, with guidance on which sizes are suitable for which situations (such as the number of bathrooms in your home). Follow the manufacturer’s guidance closely when sizing a water softener before spending your money.

Generally, a large family with very hard water will need a bigger water softener than a small family with mildly or moderately hard water.

In the table below, we’ve shared the recommended water softener size depending on your home’s total hardness and your family size.

Household Size 0-10 GPG11-20 GPG21-30 GPG31-40 GPG41-50 GPG51-75 GPG76 - 100 GPG
1 - 2 people16000240003200040000640006400080000
3 - 4 people24000320004000048000800008000096000
5 - 6 people3200040000480006400096000110000110000
7+ people40000480006400080000110000110000110000

📏 How To Correctly Size A Water Softener

Now you know what might happen if you buy a water softener that’s too big, you probably want to know how to buy the water softener size for your home.

You’ll need to know two things to correctly size a water softener:

  • Your average daily water usage (which you can work out from your water bill)
  • Your water hardness

📌 Multiply your daily water usage by your water hardness to determine the minimum grain capacity for your water softener. This will give you the ideal water softener size for your home.

We advise buying a softener with a slightly higher grain capacity than your calculation to ensure there’s enough capacity even if your water usage goes up (for instance, if you install any new water-using appliances or your family grows during your years of owning the water softener).

Here’s a much more detailed guide on how to buy the right size water softener.

❔ What If A Water Softener Is Too Big? FAQ

Do big water softeners use more salt than small water softeners?

No, big water softeners don’t use any more salt than small water softeners. The exact amount of salt used to soften your water is based on your water hardness, not the softener’s size and capacity. The harder your water, the more calcium and magnesium it contains, and the more sodium ions must be used to replace these minerals. A water softener’s capacity alone won’t result in any more or less salt being used to soften water.

Can I adjust the capacity of my water softener?

No. Your water softener’s capacity is what it is – you can’t change it once you’ve bought the softener. What you CAN do is alter the frequency of regenerations based on your water’s hardness, which you input into the control valve when setting up the unit. The harder your water, the more salt will be used in the softening process, and the more frequently the softener will need to replenish the resin by regenerating.

What’s the ideal water pressure for a water softener?

The average ideal water pressure for a water softening system is 60 to 80 PSI. 100 PSI is usually the max recommended pressure for most water softeners, although this might be slightly higher for large softeners.

  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

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