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How Does a Water Softener Work to Treat Hard Water?

Marc McCollough

By Marc McCollough
Published February 21, 2024

If you find spots on dishes and tile, white or gray deposits on faucets and you notice your soap and shampoo don’t lather properly, you may have hard water. A water softener can help, but how does water softening work? We’ll explain the process and show you how it improves your water.

A gray A O Smith water softener in a home garage.

What Does a Water Softener Do?

A water softener is a device that treats a water condition known as hard water.

What Is Water Hardness and How Does It Affect Your Home?

A chrome faucet with limescale deposits.

Hard water is water with a large amount of dissolved minerals. Magnesium and calcium are key causes of hard water, but elements such as iron and aluminum can also be factors. As hard water evaporates it leaves behind a white or gray deposit called limescale. Limescale creates spots on dishes and can accumulate in appliances and on fixtures. In some cases, limescale can clog pipes and reduce the lifespan of water-handling appliances. Hard water can also make it more difficult to get your clothes and skin feeling clean.

Benefits of Using a Water Softener

A water softening system reduces the amount of hard water minerals in the water. Soft water offers several benefits, including:

  • A reduction of spots on dishes, glasses, silverware and surfaces in kitchens and bathrooms
  • A reduction of limescale on faucets and shower heads
  • Water that allows soap to lather better and rinse away easier, leaving your skin feeling cleaner
  • Better performance from laundry detergent, giving you clothes, sheets, etc. that feel and smell cleaner
  • Reduced risk of plumbing and appliance problems from hard water mineral deposits

Good to Know

Hard water is common in many areas of the United States. Take a look at our explanation of hard water for details on the condition. Our water softener guide will help you compare different types of water softeners to find the right one for your home.

Here’s How a Water Softener Works

An AQUASURE water softener system with a resin tank and brine tank.

A standard water softener uses resin beads and an ion exchange process to capture the substances that cause water hardness.

Ion Exchange Water Softening

So how does water softening work? There are four basic steps to the standard ion exchange water softening process:

  1. Water from the municipal water supply or your well enters a tank full of negatively charged resin beads that are coated with sodium ions.
  2. As the water flows through the beads, the negative charge of the beads pulls in the positively charged mineral ions, removing the hard water minerals from the water.
  3. As the water loses the mineral ions, it collects positively charged sodium ions from the beads to replace them — the ion exchange. The soft water then exits the water softener and flows into your household plumbing system for use as drinking water, bath and shower water, etc.
  4. Periodically, the water softener goes through a regeneration process, washing the beads with a brine solution to flush out the collected minerals and replenish the sodium.

Good to Know

You may hear the term salt-free water softeners, but these devices are actually water conditioners and descalers, not water softeners. They cause the minerals to form crystals, which can help prevent the formation of limescale. Since the minerals are still present, these devices don’t soften the water. To remove the minerals, you need a salt softener. Water treated with a conditioner or descaler, however, is an option for reducing the effects of hard water and providing drinking water that’s free of the sodium the ion exchange process adds.

Water Softener Parts

There are three main water softener components:

  • The resin tank or mineral tank contains the beads that capture the minerals. Water from your water supply enters this tank for softening.
  • The brine tank contains the water softener salt solution — brine — that regenerates and refreshes the beads. You’ll add water softener salt to this tank periodically to create the brine.
  • The control valve or head valve regulates the flow of the water from your water supply into the resin tank and monitors the water flow. When the beads have collected their limit of minerals, the valve closes off the water supply and allows the brine to regenerate the beads.

Typical water softener components also include:

  • A bypass valve that isolates the softener from your plumbing system for maintenance
  • A pre-filter that helps remove impurities from the water before it enters the resin tank
  • A control panel for setting up the device
  • A motor that operates the control valve

How Water Softener Regeneration Works

A person pouring Diamond Crystal water softener salt pellets into a water softener.

As the beads in a water softener collect mineral ions, they’ll eventually reach maximum capacity and won’t be able to collect more. At this point, the softener needs to wash away the mineral ions so the beads will again be effective. This is the regeneration process. Here are the key steps for regeneration:

  1. The softener backwashes the beads with water to remove sediment. 
  2. Brine flows through the beads, washing away the mineral ions and replenishing the sodium ions. 
  3. The system rinses away the brine — now depleted of sodium ions and full of mineral ions — out of the water softener and into a drain.

Good to Know

Unless you have a dual-tank system, the water softener won’t be able to soften water during the regeneration process.

Enjoy Better Water With a Water Softener and Water Conditioning

Water softening can be an effective way to deal with the common problem of hard water and reduce limescale in pipes and appliances and on dishes, glasses and plumbing fixtures. Soft water can also make your hair and skin feel better and make your laundry look brighter and smell fresher. 

A water test can help you determine if you need a water softener. If your water tests for calcium carbonate at a level of 7 grains per gallon or higher, a water softener is a good option. If you’re not sure which water softener is best for your home, an associate at your local Lowe’s can help you find the right system. You can consider other water treatment systems as well, including:

Good to Know

While water filters will remove many types of impurities from your water and can improve the taste, they won’t remove hard water minerals.

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