How to Size a Water Softener for Household Use

When it comes to sizing a water softener, choosing the right size for your water use is very vital. Water softeners vary in sizes with each size, stating how many hardness it can remove from water before regeneration. If you choose a small-sized softener, it will soon exhaust its capacity, decrease water pressure, and affect flow rate.

Choosing a softener that is too large, on the other hand, will result to inconsistent regeneration. Either way, it will cost you more money to maintain it and keep it working at an optimum level. That is why properly sizing a water softener is essential. This article will teach you what you need to understand about how to size a water softener.

Despite the different sizes of water softener flooding the internet, the issue of incorporating water efficiency hasn’t been thoroughly factored. A vast majority of water softeners have a massive salt consumption of more than 2000 pounds a year, against highly efficient models that uses 300 pounds over the same year.

What is a water softener?

A water softener is a filtration system that removes excess calcium and magnesium minerals in the water. These calcium and magnesium minerals are responsible for water hardness.

What Is A Water Softener

Hard water is detrimental to livelihood. It makes modern homes uncomfortable and unsafe. It destroys the lifespan of some home appliances, like coffee makers, dishwashers, hot water appliances, etc. They build up as deposits in pipes and decrease water pressure. Once the temperature of your heater rises, the deposits of minerals will solidify and expand, making a cracking noise in your water tanks.

Hard water makes the laundry a living hell. You will need a whole lot of extra detergent before the water can foam. It doesn’t form lather with soap and bathing in hard water will leave your skin dry and itchy. Hard water will also leave filmy soap scums in your bathrooms, kitchen, etc. A water softener is the only solution to water hardness as it will remove these minerals, causing water hardness through ion exchange.

Why Should I Care About Efficiency?

Why Should I Care About Efficiency

You should care about the efficiency of your water softener because it dictates how much salt you have to purchase, the quantity of salt you have to add, and how much salt that gets discharged to the environment. Factoring a softener salt’s efficiency when sizing a softener will ensure that you purchase a softener that uses a minimal amount of salt. This goes a long way in cutting down costs and saving more.

How To Properly Size a Water Softener?

How To Properly Size a Water Softener

The key to properly sizing a water softener is by, first of all, identifying your water quality, use, and making sure it concurs with the size of your water softener to bring about effective soft water capacity. Five steps are involved in sizing a water softener properly. They include;

Determining your water hardness level

Like explained, hard water is water that has a high concentration of calcium and magnesium ions in it. If you can’t determine your water’s hardness level, it will result in improper sizing.

Determining Your Water Hardness Level

Water is generally classified as soft water, moderately hard water, or hard water, depending on the amount of calcium and magnesium ions in it. These amounts are measured in milligrams per Litre (mg/L), parts per million (ppm), or grains per gallon (gpg). The table below represents the water hardness chart; 

Water level






Moderately hard






These measurements determine the hardness of your water, which is essential in properly sizing a water softener.

You can determine the level of water hardness by buying test kits online or having someone test your water in the laboratory. If you use city water, you can determine the hardness level from your local water provider as an alternative. They usually publish their annual reports online.

Estimating your daily water consumption

Estimating Your Daily Water Consumption

Determining the quantity of water you use every day is the second step in this list. If you don’t want to be racking your brain and, in the end, miscalculate the result, check your water bills. It shows your total water consumption over a period. If you don’t have the luxury of accessing such information, you can calculate your average daily water use by multiplying the number of people using the water in your home by 80 (for regular users) or 100 (for extreme users). This will give you an estimated daily water consumption.

For example, if it’s a 2-person family, multiply 80 x 2, which equals 160 gallons of water consumed daily.

Calculating your daily softening requirement

Calculating Your Daily Softening Requirement

Now that you know your estimated daily water use, next is to calculate the daily softening requirement. Multiply your everyday water use by the number of hardness in the water. Hardness is 10 grains per gallon, which means that if your daily water consumption is 160 gallons, your water softener will be removing about 1600 grains daily.

Calculating your required total grain capacity

Regeneration is the process of washing and draining away minerals that have accumulated in the resin bed with either sodium or potassium. A water softener is only able to remove as many as hardness grains as possible before it regenerates.

Calculating Your Required Total Grain Capacity

As the softening undergoes, the resin beds inside the tanks will likely get saturated. It may not get saturated immediately, but it will, at some point. And when it does get saturated, removing calcium and magnesium ions will be limited or restricted.

Usually, a water softener is sized to regenerate about once in every week. Most experts advise this to improve high softening efficiency, protect the head valve against wear, and also conserve the resin bed, ensuring it is safe from iron and sediment.

Your total grain capacity is determined by multiplying your hardness grains by seven days. In this case, it is 1600 grains x 7, which equals 11,200 full-grain capacity per week.

Considering salt efficiency

Considering Salt Efficiency

From calculations, a water softener can regenerate about 11,200-grain capacity in a week without having to run out of water. However, this is still mere estimates because we haven’t factored in salt efficiency or brine efficiency as it’s called sometimes.

This is the trick to all this - most people are unaware that partial regeneration is more efficient and less costly than full recovery. That is because regenerating a resin bed to 100 percent will take up a large amount of salt, which is a little on the high side. And if a resin bed isn’t regenerating to 100%, it will likely to exhaust faster.

Take, for instance - a 15,000-grain capacity system would be ideal for you since you want to remove 11,200 hardness grains from water. What you do not know is it will take about 20 pounds of salt to regenerate the system to 100%, which is massive. It will take about 24 pounds of salt to fully regenerate a 24,000-grain water softener capacity system to 100%, which is still on the high side.

However, if you regenerate about 45% of the resin beds, it will take less amount of salt when you compare it to regenerating about 88%. What this means is since you have 11,200 hardness grains per week, you should choose a higher grain capacity of 33,000 and above. 45% of 33,000-grain capacity represents about 14,850 hardness grains, which means you have regenerated 11,200 hardness grains to 100% with less amount of salt and less exhaustion.

A 33,000-grain capacity removing 11,200 hardness grains is more efficient than a 15,000-grain capacity removing 11,200 hardness grains because of it’s of bigger capacity. It will result in fewer costs on salts in the long run and less salt discharge, which affects efficiency.

Considering flow rates

A water softener is as good as its softening capacity. However, you can’t expect your water softener to deliver soft water into the entire house all the time at an optimum level. Sometimes, you may experience hard water that may leak through. This may not be surprising, but when it does leak through, the results will likely be a decrease in pressure and flow.

Considering Flow Rates

For instance, this incident often happens in the morning, where there is a rush to meet work and school schedules. Different showers will be on; taps will be running simultaneously, there will be a lot of dishwashing in the kitchen, and so on.

So, you need to pay close attention and observe your water carefully flow rates. The usual standard for measuring flow rates in gallons per minute or GPM for short. Large homes do require higher flow rates than small homes. In that case, families should get systems that will provide gpm that will be sufficient. We advise that large families should use a minimum of 15 gallons per minute, while small families should use less. 

Water Softner Calculator

A water softener size calculator is a way of calculating the ideal size of your water softener, based on a variety of parameters like water conditions, water consumptions, required total capacity of regeneration, and softening requirement.

Why should I buy an efficient water softener?

For the world of Waterloo, it is thought that 134,723 household water softeners use about 2.7 billion liters of water and 44,700 tons of salt for softener regeneration per year.

It is same as more than 10 Olympic sized swimming pools having full of water, and 1/3 of the weight of CN Tower in salt.

Dissolved chloride and sodium ions end up drinking water supply and the Grand River supply. To use water for resin, regeneration is the wastage of water resources.

This may seem the flushing money down of the drain; it also affects the quality of water. A good type of water softener costs as much as 400 dollars a year in salt and water to operate.

The average requirement initiated softener at present in the market would cost three people household about 200 dollars a year to do work.

The exact water softener uses less water and less salt. It is good for the wallet, our community, and the environment.

Watch how to size your water softener

How to Size a Water Softener FAQs

Can a water softener remove iron?

Yes, it can remove iron when it’s in a soluble state.

Does the size of a water softener affect efficiency?

Yes. Water hardness determines the size of a water softener. If you choose an extremely large water softener and an extremely small softer, it will affect regeneration, which is essential for water efficiency.

When can you replace a water softener?

Water softeners can last for a very long time if properly maintained. Typically, it can last for 15 years or more.

I use well water at my house. How can I determine the level of water hardness?

Most wells have so much iron content, which affects the quality of water. To know if your well has one, you will get brown stains on your fixtures.

If a water softener develops a fault, can I replace it?

 You can replace the water softener.

Final Words & Recommendations

A water softener is an effective solution to curbing water hardness and ensuring your water is safe for drinking. However, to adequately size your water softener, a couple of factors and steps are considered that have been explained in this article on how to size a water softener.

Properly sizing a water softener is ideal and will go a long way in determining the amount of required hardness in water it has to remove without exhausting its capacity, breaking the valve, and reducing its efficiency.