Sunrise Specialty » What Size Water Softener Do I Need for a Family of 4?

What Size Water Softener Do I Need for a Family of 4?

Before choosing the right size of water softener for your house, you have to decide which type of device you need. It is not the same if you want to install one faucet or a whole house water filter. In general, there are three types worth of consideration, ion water softener, salt-free water softener, and reverse osmosis system.

Each of them has unique specifications and guidelines. So, you should think on time about the efficiency of the softener, environmental protection, and the space you can provide for installing the system, as well as its price and quality. Picking out the best size of the system for your home will depend on the water flow, the amount of water you need, its class, and the softening requirements of the system.

What size water softener do i need? – Water Flow

In case you want to install the water softener for the whole household, you should calculate the overall water flow. Don’t forget that often more than one source of water is turned on. For example, you can use a washing machine and a kitchen sink faucet at the same time.

Calculate how many water users are there in your home, including all faucets, a washing machine, toilets, and garden sprinklers. Each of them uses a certain number of gallons per minute while working. Don’t forget to add how many devices you usually use at the same time.

It is essential to choose the appropriate water softener size. Otherwise, you may get lower water pressure. Consequently, it will result in bad filtrating, harder water than anticipated, and improper filtrating of iron.

What Size Water Softener Do I Need for a Family of 4?

If you want your system to work efficiently and provide enough purified water for all family members, you need to calculate the average amount of water used in your household.

The water usage standard in the US is 75 gallons (284 l) of water per person in 24 hours. It is more than 300 gallons (1,136 l) of water per person daily. On average, the daily spending of every American includes:

  • Shower – 11.6 gallons (44 l)
  • Toilet – 18.5 gallons (70 l)
  • Washing machine – 15 gallons (56.8 l)
  • Dishwasher – 1 gallon (3.8 l)
  • Faucet – 10.9 gallons (41 l)

However, if the water in the region you live in is too hard (heavy water), it is better to calculate 100 gallons (378.5 l) per person for a day.

The calculation is not too hard. If 4 members of your family live in your household and the water in your region is extremely heavy, you should multiply 100 gallons (378.5 l) of water per person with 4.

That means the water capacity in your household is 400 a day. Keep in mind that that amount of water includes all daily usage, including cooking, washing, showering, and drinking.

Also, you need to calculate water usage differently depending on the system you want to install. For example, some reverse osmosis systems use 4 gallons (15 l) of water to get 1 gallon (3.8 l) of filtered water. Therefore, the system will use more water than expected by an American water usage standard.

Luckily, contemporary RO systems have pumps that may take water back to the system. That means you don’t need to worry about the amount of water you spend.

Water Quality 

The water quality is the most complicated issue when deciding which size of softener to choose. You can determine the quality of water by yourself or ask the municipal water supplier for the details.

In case you use the water from the well, or you can’t ask anyone, you can purchase a water quality kit and test water in your house. The primary issue is to determine the level of hardness.

There are four basic types of water, soft, moderate, hard, and very hard. Read instructions in the kit carefully, and test the samples according to them.

Then send the results to the water centre in your local area to check them for you. It is crucial since every water softener system has unique specifications for different types of water quality.

Softening Requirements

Softening Requirements
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Once you calculate the quantity of water you need daily, you can determine the softening requirements. Let’s take some standards if you know that 1 grain (17.1 parts per million) is a unit determining the water hardness.

For example, imagine that the results of the test show that the hardness of the water in your house is 10 grains per gallon. Now, if you have a household of five members who spend 500 gallons (1893 l) of water per day, you should multiply 10 grains per gallon with that result.

That means a daily softening requirement for your household is 5000 grains when you use any softener except reverse osmosis. You can quickly understand that you need a water softener that can filter 35 000 grains per week.

When you have the precise number (35000 grains in this case), you can look for the necessary capacity and ideal size of the water softener for your home. Keep in mind that you always need to use the requirement for one week. It is a reference since you should clean the system once a week.

If you want to install the reverse osmosis system, you need to calculate the amount of water your household used daily. Keep in mind that it makes 50 to 75 % of the required gallons per day.

Therefore, you need to purchase the model that has 25 to 50% bigger capacity than the specified number of gallons for your household per day. That way, you will get the full efficiency of the system.

Free Space for Water Softener 

The water softeners come in different sizes, which often determine their capacity. Therefore, you should measure the space where you want to install your new unit before going shopping.

After measuring the height, width, and depth of the device, you should calculate free space next and above the filter system, as well. You will need space when pulling the filters up, for example. Plus, add some space for an additional pressure pump and water containers.


When you make all the necessary calculations and measurements, you will be ready to purchase your new water softener. Since most of them have a 5 to 20 years guarantee, the right choice means a long-lasting and carefree future regarding clean water for your family.