How Does a Water Softener Work

​​Ever wonder just exactly “how” a water softener works to remove the hard minerals (calcium and magnesium) from your water. Well, keep reading! By the end of this blog post I hope you will have a solid understanding of why it’s important to have a water softener and how it works.

Naturally occurring calcium and magnesium minerals in the water can result in numerous issues for a home. The presence of these elements in the water is commonly referred to as “hard water”.

​Some of the implications include:

  • Scale build-up on faucets
  • “Spots” on glassware and glass shower doors
  • Clogged pipes with scale build-ups
  • Damage and extra wear and tear on appliances

If you have experienced any of the above, finding a solution to your hard water problem is critical. The most effective way to deal with hard water is by installing a salt-based water softener. It is designed to eliminate the hardness from the water in your home. The functionality of a water softener is embedded in its ability to impact the entire water supply of a house. There are numerous sizes of water softeners you can choose from, depending on how many people are in the house and how much water is consumed in the household. Regardless of size, all water softeners generally work the same way. All water softeners are connected to the main water supply valve in a house via the loop. This way, all the water used indoors will be treated by the softener. If the home does not have a loop installed, no problem. Often times soft water loops are retro-fitted to a home in order to facilitate the use of a water softener.

The Three Steps to Water Softening
A successful water softening process is comprised of three steps. Here is a high-level overview and we’ll dive into more detail of each step as we move thru this blog.

  • Ion Exchange
  • Regeneration & Backwash
  • Fill Cycle

Step 1 – Ion Exchange Process
As the water enters the house and passes thru the loop, it goes directly into the resin tank. While in the tank, the water completes an ion exchange process. This refers to the exchange of the calcium and magnesium ions with the sodium chloride (salt) ions (potassium may also be used) in the resin.
The resin attracts and binds to the hard-mineral ions and release a sodium ion into the water. The softened water is then distributed thru the plumbing system via the cold-water supply lines to all areas of the home. Another line carries the softened water to the hot water heater to provide softened, hot water throughout the house as needed. The actual ion exchange process is very simple…but critical to fully remove the hard minerals. Don’t be fooled…without salt in the process the hard minerals are not removed and remain in the water flowing thru your house.

Step 2 & 3 – The Regeneration and Backwash Process
The regeneration cycle is when the brine water from the salt tank is pumped through the resin, replacing the calcium and magnesium ions with sodium or potassium ions. In the backwash cycle all the brine that has passed through the resin and the hard minerals are drained out of the system. Once the resin has facilitated the exchange of ions for a specific amount of water consumed or duration of time, the system will need to regenerate (or restore) the resin bed. If the resin becomes full of calcium and magnesium ions, there are no more receptors for them to bind to. There is basically no “space” available to receive the ions and the process of water softening will be futile. Regeneration revitalizes the resin bed with more sodium ions to continue the softening process.

The regeneration cycle is typically programmed during initial installation within the valve setting to occur when demand for water is low, usually late at night. Water in the salt bin, also known as the salt brine, is released into the resin tank. During this process, there is a 2nd ion exchange in which the resin bed releases the calcium and magnesium ions, and they bind to the sodium ions that are in the brine water.
There are two methods of regeneration depending on the functionality of the valve…up-flow and downflow of the water. The type of water flow regeneration a machine provides could make a significant difference in the overall efficiency of the because it impacts the number of times the salt tank needs to be refilled and the amount of water used in the process. The valve type on the machine will determine if the water softener uses an up or down flow. Some machines have valves with the capability to utilize both flow types depending on how you set the valve.

  • Up-flow – The connection between the resin tank and the salt tank is strategically placed to allow the brine water from the salt tank to be pumped from the bottom of the resin tank to the top. When it reaches the top, the brine water is transferred to the drainage system and is backwashed (emptied) out of the entire system. With this process, you reduce the amount of water and salt used to clean the resin bed since it takes one run-through to get it ionized.
  • Downflow – The brine water from the salt tank goes into the resin tank from the top and needs to flow to the bottom of the tank, then move back to the top where it is backwashed (emptied) out of the system. In this type of system, there is a need for a second rinse of the resin bed since the brine water as taken the calcium and magnesium ions has passed through the ionized resins. This increases the likelihood of another ion exchange happening.

Flow rates measured in gallons per minute (gpm) during the regeneration and backwash cycle, is also important to consider. The higher the flow rate (gallons per minute) the shorter the overall cycle time. Flowrates also impact the overall water pressure of the house if other demands for water occur at the same time.

Determining the Regeneration and Backwash Frequency
Most water softeners come with two options to set the frequency of the regeneration and backwash cycles. In the first option, demand-initiated regeneration, the valve is set to run the cycles automatically based on the number of gallons of water softened, as monitored by the valve. For instance, the valve might be preset upon installation to initiate the regeneration and backwash process once the resin has softened 1500 gallons of water. This accounts for peak periods of water usage, say when there is company visiting and adjusts the cycle to run accordingly since the demand for the amount of water softened will increase. The opposite is also true. When out of town for vacation, the monitoring system in the valve will recognize that less water is being softened…and delay the backwash and regeneration cycles. This ensures the process only occurs when necessary. This is the most user-friendly and efficient method.

The other option is to run the regeneration and backwash cycles based on a set number of calendar days. In this example, the valve controls would be set to run the cycle every 5th day at 2 am, regardless whether the resin bed needed refreshed. For households that do not use a lot of water, a calendar setting will lead to usage of more water and salt than necessary because it’s running on a set calendar vs actual usage. On the other extreme, if water usage is peaked…the resin bed may fill up quickly and stay full for several days before the selected calendar date to run. This will degrade the performance of the machine to provide softened water because the resin bed is full.

The basis for setting how often the regeneration and backwash cycle can occur is also dependent also on the size or capacity of your water softener. Large capacity water softening tanks (as measured in terms of diameter and height) with a larger quantity of resin grains will have more capacity for an extended timeframe between cycles. For example, a smaller 32,000-grain machine will need to run the cycle more often than a 64,000-grain machine.
It is recommended to consult a local water softening professional to provide a proper analysis for sizing and installing a water softener. If the units are improperly sized or designed there is a potential for not having softened water when needed or impacts on the overall flow rates for all water needs in the home.

Step 4 – Fill Cycle Process
The brine water in the salt tank is refilled with water automatically by the valve. Salt is added manually to facilitate the creation of the next batch of brine.

Maintaining a Water Softener
It’s important to maintain a water softener to ensure optimal performance for many years. Generally, maintenance includes keeping an eye on the levels in the salt tank. Salt should only fill the tank 2/3 of the way. Periodically check the salt levels in the salt tank. If the salt falls below 2/3 of the tank height, simply add more salt. It is recommended to check the salt tank monthly. Check your valve for drips and leaks. If you notice any leaks call your installer right away. Putting the system into “by-pass” mode is also recommended when being gone from your home for extended periods of time (i.e. snow-birds)
Keep in mind a salt-based water softener is the preferred method for protecting your home against harmful build-up from minerals in the water. However, the salt-based water softeners will not provide water filtration for your home (i.e. chlorine removal, improve taste, odors, etc.) For whole house water treatment system options contact AZ Water Solutions today.