How Does a Water Softener Work? All Your Questions, Answered

Updated: Jun. 14, 2024

Many households throughout the country have hard water. If yours is one of them, let our experts explain why and how to install a water softener.

In my home, we get our water from a deep well, and—as is often the case with well water—it’s hard. Ever since I learned how to install a water softener from a local plumber, we’ve had a welcome respite from the problems hard water causes around the house.

What is hard water, you ask? Well, in the simplest terms, it’s water with a high mineral content, but there’s a more precise definition. According to Kelly Russum, a plumber who serves California’s Coachella Valley, water analysts measure hardness in GPG (grains per gallon), where one grain is 64.8 mg. of calcium. “Soft water has GPG lower than 1, and hard water is considered when GPG is 7 or more.” In other words, a gallon of hard water contains half a gram of minerals — usually more.

Water with a high mineral content causes all sorts of problems, including:

  • Mineral stains on bathroom fixtures, faucets and other appliances;
  • Sediment buildup in water heater tanks;
  • Blockages in faucets and plumbing pipes;
  • Dry hair, itchy skin and reduced effectiveness of soap.
  • Foul-tasting and discolored drinking water. This is primarily caused by iron, which is one of the minerals commonly found in hard water.

You don’t have to get your water from a well to have hard water. Community water in many municipalities is also hard enough to cause mineral stains and make showering unpleasant.

The solution is to install a water softener. Our experts explain what that is, what different types are available and what’s involved with installation and maintenance.

What Is a Water Softener?

A water softener is basically a filter, but unlike one that removes chlorine, pesticides and heavy metals, it’s designed to remove minerals like calcium, magnesium and iron from the water supply. A typical system consists of a cylindrical inflow tank ranging in diameter from eight to 14 inches and in height from 44 to 65 inches and a separate brine tank containing a solution of sodium chloride or potassium chloride.

“There are whole-house water softeners and under-counter water softeners,” advises South Carolina-based plumber Justin Cornforth. “I recommend opting for whole-house systems because they ensure that all appliances in your home and plumbing systems receive softened water.”

How Does a Water Softener Work?

Josh Rubin, a Certified Restorer from Phoenix, AZ, explains the operation of the salt-ion water softener: “It works by removing minerals, primarily calcium and magnesium, from hard water through a process called ion exchange. Put simply, that’s a way to remove and replace the minerals that cause hard water.”

A water softener tank contains a large quantity of resin beads, forming the bed through which water flows into the building. The beads are charged with sodium or potassium ions supplied from the brine tank, and as hard water passes through, the mineral ions are electrically attracted to the beads and displace the sodium or potassium ions, which take their place in the water. “In this process,” says Rudin, “salt is liberated into the water while calcium and magnesium are pulled out.”

The beads eventually become saturated, so the system has to complete a regeneration cycle every week or so. In this cycle, the brine solution is flushed through the tank to restore the salt ions and wash the accumulated minerals down the drain. Most systems do this automatically.

Types of Water Softener Systems

You can choose from one of three types of water-softening systems:

  • Salt-based: This is the type described above. “They are the most common and effective type for significant hard water issues,” according to Asif Bux, a plumber from Calgary, Alberta.
  • Salt-free: These systems, according to Russum, use potassium chloride instead of sodium, acting as water conditioners rather than removing minerals. “People concerned about sodium consumption may prefer these types of softeners,” he advises.
  • Reverse osmosis: Cornforth explains, “Reverse osmosis water softeners are a good option for homes where you want to remove a wide range of contaminants such as PFAs, TDS, chlorine, heavy metals, VOCs, odors, rust, sediment and more.” They are generally point-of-use rather than whole-house systems.

Advantages of Having a Water Softener

All our experts agree with Russum, who says that soft water will positively affect your plumbing system. “It won’t leave mineral deposits in your pipes, and as a result, you can also save money on your energy bills because, with scale-free pipes, your water heater won’t have to work as hard.” Some other benefits include:

  • Longer-lasting home appliances;
  • Elimination of hard-to-clean minerals stains;
  • Improved soap efficiency;
  • Softer skin and hair.

Downsides of Having a Water Softener

Rudin and Bux point out that extra maintenance and installation costs are downsides to a water softener system. They also cite the potential dangers of elevated salt content in soft water for people with certain health issues and the negative environmental consequences of disposing of brine wastewater. It’s worth noting that you can mitigate these problems by choosing a system that uses potassium instead of sodium.

Russum also flags elevated salt content as a potential problem and adds two more: “The process used to soften water also makes it more volatile, which means it collects more unwanted elements from your pipes. These elements can include lead, making it potentially more dangerous. A water softener wastes up to 120 gallons of water for every 1,000 gallons, so you’ll notice a noticeable increase in your water bill.”

How to Choose a Water Softener

The two most important considerations in choosing a water softener system are the hardness level of your water and the amount of water you use. According to the Department of Energy, weekly grain capacities (number of grains the unit can handle before regeneration) of 16,000 to 32,000 are suitable for small houses, apartments and RVs, while medium to large households would need a grain capacity from 40,000 to 100,000. Many manufacturers and retail sites offer charts that allow you to choose the correct size based on your usage and the hardness of your water (which you can determine by sending a water sample to a lab for testing).

How To Install a Water Softener

A typical water softener consists of two tanks: the softener tank that contains the resin beads and the brine tank. Here’s a quick rundown of the installation process:

  1. Install a bypass loop in the building’s water supply. One leg of the loop directs water into the tank, and the other one directs the outflow back into the water supply.
  2. Connect the brine tank to the softener tank. You usually do this with plastic tubing that is supplied with the unit.
  3. Install a drain pipe from the brine tank to the sewer. If it’s close enough, plumbers often make this connection at the washing machine standpipe.
  4. Wire the controller that regulates automatic regeneration into the building’s electrical system. This often involves just plugging it into a standard receptacle.

How Much Does it Cost to Install a Water Softener System?

“The most basic, entry-level softening systems start around $500 for just the components themselves, not including installation,” says Rudin. “It’s possible you can get it done for less than this, but it would require massive deal hunting — and possibly a number of failed softening systems — before success.”

Bux and Cornforth put a high end on equipment costs between $2,500 and $3,000, and when you factor in labor, Russum warns the maximum cost can be as high as $11,000. However, Russum warns that it’s almost impossible to answer this question definitively.

Can You Install a Water Softener Yourself?

If you have the plumbing skills, you can probably install an under-counter water softener yourself, but trying to install a whole-house system is a different matter. “It’s not an easy task, and if you don’t know exactly what you are doing, it’s certainly possible to cause damage in the process of installation,” says Rudin. Russum adds that some regions may require a licensed plumber to perform the installation.

How Often to Add Salt to Your Water Softener

Some systems have low-salt indicators that alert you when it’s time to add salt. In the absence of an indicator, you need to check the salt yourself and add more when it falls below the required level. Bux recommends doing this every four to six weeks.

Should I Use Salt Pellets or Crystals?

Bux recommends pellets. They cost more than crystals, but they don’t have any additives, which means purer water overall. Moreover, they don’t dissolve as quickly, so they last longer in households with particularly hard water. However, check the requirements for your system before purchasing salt. Cornforth warns that using the wrong type of salt that can cause clogging and inefficient operation.

About the Experts

  • Kelly Russum founded KC’s 23 ½ Hour Plumbing in 1978. He has been the go-to plumber for countless Coachella Valley residents ever since.
  • Justin Cornforth is the owner of Ace Plumbing, Electric, Heating & Air, based in Anderson, SC. It’s a family-owned company founded in 2017.
  • Josh Rudin is a Certified Restorer and the owner of ASAP Restoration, LLC, serving Phoenix, AZ and surrounding areas.
  • Asif Bux is the owner and service manager of Comfort Union, a licensed HVAC, Plumbing and Electrical company located in Calgary, Alberta

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