What Size Water Softener Do I Need?

When you decide to purchase a water softener, you will want to know what size it should be to properly treat your hard water. But how do you do this? 

Online tools may help with this, but you must know exactly what to look for in a water softener. More vitally, you should understand a water softener’s capacity and efficiency. 

What Size Water Softener Do I Need

We have covered all the aspects of buying a suitable water softener for your home, from calculating water hardness and consumption to how efficient water softeners really are. 

Sizes Of Water Softener

The most common sizes of water softener on the market are 24,000, 32,000, 48,000, 56,000, and 64,000 grain capacity.

Grain capacity refers to the level of hardness in the water, measured in grains per gallon, that the water softener is able to remove. A grain is the equivalent of 1/7000th of a pound.

The figures relate to the number of grains of hardness that the softener can remove from your water supply before it regenerates.

Regeneration typically occurs once a week and flushes the hard water ions from the resin bed in the softener. 

To find the best-sized softener for your home, calculate the hardness of the water coming into your home and estimate your household’s average weekly water consumption. 

Multiply these two figures to get the number of grains that your water softener needs to remove each week before it needs to regenerate. 

Manufacturers and dealers estimate the capacity of their water softeners by testing under laboratory conditions.

In the real world, it is advisable to allow an extra 30% capacity to account for differences in water temperature, pressure, and flow rates. 

Calculating Water Hardness

Water hardness is the measurement of how much calcium and magnesium are dissolved in it, which is vital to know before you buy a water softener.

Guesswork will result in an unsuitable system for your home and frustration on your part. 

It isn’t difficult to test the water yourself with a home test kit if you have a well. If you live in a town or city, your local water board can tell you your water hardness.

The measurement will either be in grains per gallon (GPG) or milligrams per liter (mg/L). 

When you set up your water softener, it will ask you for the hardness measurement, so it is important to have this information at hand. 

The hardness of the water will be a deciding factor in which softener you need, as you will need to match its capacity to your water’s hardness as well as your consumption.

And as we will see, the capacity and efficiency of the water softener will be very important to get right. 

Other minerals will be present in your water sample, but the only one that should affect the hardness result is iron. If there is iron in your water, you will need to add 3 GPG of hardness for every 1 mg/L of iron. 

Average Water Consumption

Average Water Consumption

The second part of your calculation for determining the size of the water softener that you need is to measure your water consumption.

This can vary depending on the season of the year, but an average at the top end of usage should compensate for any discrepancies.

The easiest way to do this is to look at two or three recent water bills and average out how many gallons of water your household uses per month.

It helps to break this down into weeks, as a water softener will usually regenerate once a week. 

If you don’t have a recent water bill to hand, you can make a rough estimate of how much water you use by multiplying 75 gallons a day by the number of people in the household. 

Softening Capacity

So now you have the hardness measurement of your water and your average weekly water consumption. With these, you can calculate the required softening capacity of your water softener. 

As an example, if your water hardness is 9 GPG, and your household consumption is  375 gallons of water per day, then you multiply these together:

9 x 375 = 3,375

Therefore, your system will need to take out 3,375 grains of hardness per day or 23,625 per week. 

You would probably choose a water softener with a 24,000 grain capacity for your needs. However, we need to talk about water softener efficiency before you make a decision. 

Water Softener Efficiency

When a softener is hailed as removing 24,000 grains of hardness, this is under optimum conditions where the temperature, pressure, and flow rate are carefully controlled. In an average household, that doesn’t happen. 

The problem lies in regenerating the system to this 100% capacity. To do this, you need a huge amount of salt for each regeneration cycle. This of course will cost you a lot of money in bags of salt. 

If, however, you buy a softener that is a third bigger than your calculations indicate, then you can use less salt.

While the initial investment for a bigger system will be more, you will recoup this cost in a short period by using much less salt for a weekly regeneration. 

Basically, you are not trying to max the system out, so the smaller amount of salt can more than adequately flush out the resin bed of hard water ions. 

In Conclusion

We hope that our guide to sizing a water softener for your home has helped to illustrate the more important aspects to consider before purchasing one.

Understanding how the system works, as well as your softening requirements and how to maximize the system’s capacity, should make your decision that much easier.


Mandy Anderson
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