What size water softener do you need? We’ve calculated it for you

Written by Jason Hutchinson
7 Min read
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When do you need a water softener?

If you’re noticing issues like leftover residue on your plates, dry skin after showering, or soap scum in your sink, it’s possible that your home has a hard water problem that could benefit from a water softener.

Hard water affects a high number of homes all around the world, it’s not the end of the world, but it will affect the way that lots of the water appliances in your home work.

This is where water softeners come in, they do lots of things that will just improve the quality of your water, it’ll be better drinking water, less build-up in your shower heads, taps, and kettles, and even your clothes will feel better after being in the wash!

Water softeners come in a wide variety, however, and it can be difficult to know what you need. There are different sizes, and bigger isn’t necessarily the best.

Throughout this article, we’ll have a look at finding that perfect water softener for you, as well as a little more information on how it works and what your house needs.

What actually is a water softener?

illustration of a water softener system

The water supply in certain homes will get a build-up of calcium and magnesium and other dissolved minerals, and this mineral build-up creates ‘hard water’, which will create hard deposits in things like pipes and shower heads. The water softener is a filtration system that stops all these minerals from getting through.

These minerals will very rarely pose a health risk, only in people with a history of kidney stones, in which the problem could re-occur.

The problems that people tend to notice the most that affect them are the residue left behind on your plates and cutlery, or problems lathering your hair properly. The more serious problems that affect your quality of life heavily are an obstruction of water flow, corroding of your pipes, and a reduction in pressure. When your pipes corrode, the repairs are expensive, and if it gets as bad as a replacement, it becomes even more expensive.

Water softeners are the handy little things that prevent this.

They use negatively charged resin beads to attract the positively charged minerals and bring them out of the water. The mineral-less water then flows through your pipes into your home. These resin beads do have a certain amount of capacity, though, so will only do this until they’re full.

Once full, the resin beads are flushed with salt or potassium chloride, which washes and discharges them so that they can return to their original process of softening the water.

How Big Should my Water Softener be?

There are two main factors that you will need to take into consideration when deciding the size of the water softener, and those are daily consumption and the hardness of the water.


Finding out how hard your water is, is the first step. Your water supply can have a whole host of different minerals, but calcium carbonate is the most common, it’s found in marble, limestone, and chalk. The hardness of your water will usually depend on where you live, too.

It isn’t surprising at all that calcium carbonate is the most common mineral we find in our water supply, over the millions of years it formed it now makes up 4% of our crust! You still shouldn’t be seeing too much of it in our water, though, so should still be trying to fix it.

Other minerals like iron, zinc, copper, and magnesium can be in your supply too, and again, it will just depend on where you live, as well as a couple of other factors like the quality of the soil and the run-off from rain and floods.

There is a water-testing it that you can buy online that will tell you how hard your water is. You can also request a quality report from the people that supply your water, or get an independent laboratory somewhere to test a sample of the water from your house.

Water hardness is measured as the number of minerals in a certain amount of water, in either milligrams per litre (mgL) or grains per gallon (gpg).

Water Softener Calculator

Using these two figures that we’ve worked out before we can use the water softener calculator, and it’s not too difficult to do. Multiply the hardness number by the number of gallons per day that you use.

An example of this is that three people use 240 gallons in total and a hardness of 8 is 240 multiplied by 1920, so your water softener needs to remove 1920 grains every day.

slightly hard61-1203-7
very hard180+11+

Now that you have what is called your hardness value, you’ll have an understanding of whether your water is hard, soft or somewhere in between. It’s an important figure you’ll need to remember for later!


The next thing that you have to do is figure out the amount of water that your household consumes, and the best way to do this is to just have a look over your water bills from the last couple of months and figure out roughly how many gallons that you use, people tend to use a little more in summer so watch out for any fluctuations like these that can put a spanner in the works.

If for whatever reason you don’t have access to your water bills then you can use the rough estimate from the USGS that the average person consumes 80–100 gallons of water a day. Multiply this number by the number of people that are usually living in your household for a very rough estimate. Take into account things like if you’re a person who takes short showers, or if you water your garden or not. You can use this to aim toward the low or high end of the estimate.

illustration of a water softener system

Choosing the Right Water Softener

Grain Capacity

Water softeners are measured in how many grains can be removed before they need to be regenerated by salt or potassium chloride. This regeneration process tends to happen every seven days, and the most common sizes for water softeners are 24,000, 32,000, 48,000, 56,000, and 64,000-grain capacity. You should go over what you need a little bit just to allow for a little bit of excess and worse comes to the worst you’re covered. About 30% excess room is ideal, but you will know your own home and how much water you’re likely to use much better.

If we use that water softener calculator to reach 2,560 grains per day, then that amounts to 17,920 grains a week (multiplying that number by 7), and a 24,000-grain capacity is ideal as it allows for a good amount of excess space.


The cost will have a lot of variables that will affect the cost, it can be anywhere between $300 and $4000. Some of the things that you can expect to make a difference in the cost are the size, brand and features that come with it. Some water softeners can come with features that will tell you when salt needs to be added to allow for regeneration or even ones that will regenerate at night when water consumption is low.

Some states have certain regulations on salt water softening systems, so make sure to look into that before you purchase anything. Salt-free models are available, but they will cost a little more, so be prepared for that.

What Happens If I get a Water Softener too big?

You’re looking for a water softener that’s slightly too big for your needs to allow for excess, but also not too big so that it won’t get relatively full often.

If the water softener that you buy is too large for your household, it won’t regenerate often enough, which causes some problems for the water softener as it promotes bacterial growth when the resin beads aren’t regenerated.

What is a Good Number for Water Hardness?

If you’re looking for 0-3 gpg ideally, setting your water softener to the current hardness value of your household’s water is important for the water softener to work at removing grains at the optimum range.

When you are in between that 0-3gpg range, your water will taste much silkier and the plates will look a lot shinier without that residue that hard water leaves. Water can still contain some traces of those minerals we mentioned before, but without the high concentration, you’ll feel the difference in about anything you do in your home with water.

Is it Possible to Install your Own Water Softener?

Replacing a water softener with a new one isn’t a very difficult thing to do as the majority of the structure is there for it, you just have to switch the old one with the new one.

Installing a whole new one into your house though is a lot more difficult, it’ll require knowledge of pipe-cutting and soldering as well as the local laws that surround plumbing. If you aren’t sure of all of these things, it is probably best to leave it to a professional.


Water softeners can seem like an extremely complicated thing at first but take it step by step, and you’ll feel the benefits in lots of aspects of your life. Your plates will look shinier and the water will even taste better! Always allow for a little excess when looking at what size to buy, and if you are worried about installing – contact a professional!

Can your water softener be too big?

It is good to allow for a little bit of excess in the event that you happen to use a lot more one week than another, but a water softener too big will damage the resin beads as they won’t be regenerated as often as they need to be.

How do I know what size water softener I need?

There is a water softener calculator that you can use to figure out the size that you need. You need a rough estimate of how many gallons of water a day you use, and then you need to multiply that number by the hardness of your water.

What size water softener do I need for a family of 4?

The average person consumes around eighty to a hundred gallons of water a day, so figure out roughly how much the average person is consuming in your household and multiply that number by the hardness of your water, and allow for a thirty percent excess.

Appliances made simple. 

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