How to Install a Water Softener

Water softener unit installed and connected to water supply tubes

The Spruce / Kevin Norris

Project Overview
  • Working Time: 6 hrs
  • Total Time: 1 day
  • Skill Level: Advanced
  • Estimated Cost: $800 to $10,000

The term "hard water" refers to a potable water supply that contains a high level of dissolved minerals—mostly calcium and magnesium. Excessively hard water can damage plumbing pipes and appliances, it can cause problems for bathing and washing clothes, and it can affect the taste of water used for drinking and cooking. Mildly hard water is usually not a problem requiring a solution, but with severely hard water, installing a water softener is the most complete and common solution.

When Does Hard Water Require Softening?

At one point, water softener companies successfully convinced most homeowners that they needed water softeners. This trend has changed in recent years, and state health departments now recommend that water softeners are advisable only when tests show that the mineral content of the water exceeds 7 grains per gallon. If you have excessively hard water, a water softener can improve its taste, reduce water spots on dishes, prevent scale buildup on pipes, and improve the ability of soap to clean dishes and clothes.

But be aware that softening water can have some negative effects. In some cases, softened water can corrode pipes, leading to elevated lead and copper levels in drinking water. A water softener can also cause increased sodium levels in drinking water, and the automatic recharge cycle in a water softener causes sodium to be sent into the environment via the sewer system. And the process by which water softeners regenerate also wastes a considerable amount of water.

Before installing a water softener, make sure that you truly need one, and weigh the possible negatives. If your water test shows a hardness level of about 7 grains per gallon or less, there probably is no reason to consider a water softener.

Preliminary Steps

Before installing a water softener, have the hardness of your potable water supply tested. Knowing how hard the water is ahead of time will help you determine the proper settings for the softener, and it can help you decide which water softener system is right for you.

Water hardness information may already be available from your community's water utility department, which should have precise measurements of the mineral hardness of the water supply. In some areas, especially those that draw water from lakes and rivers, the water supply may be sufficiently soft that no homes require water softeners. In other regions, especially those that draw water from wells, the hardness may be high enough that all homes will benefit from softened water.

There are also DIY test kits available, similar to those used to test swimming pool water. These water quality tests can be purchased at any home center or hardware store, or from online retailers.

Before beginning installation, you'll need to select a location for the unit. The water softener needs to be positioned where it can condition the indoor potable water supply, but not the pipes leading to outdoor water connections. Softened water can damage or kill living plants, so you should install the water softener so that unconditioned water can still flow to outdoor spigots and lawn irrigation systems. Check the unit’s instructions for the recommended uses of the softened water.

Find a suitable flat location for the water softener, accessible on all sides. All water softeners make use of two tanks: a mineral tank (sometimes called a resin tank) which contains plastic resin beads that capture hard minerals through an ion-attraction process, and a brine tank containing salt or potassium chloride solution that periodically pumps water through the mineral tank to wash and regenerate the plastic resin beads. In some models, both tanks are combined in one convenient unit. Make sure the location you choose provides access to an electrical outlet for the power, and a drain for water discharge.

Installing a Water Softener

Because the chemical method by which a water softener removes minerals from water can be a little difficult to understand, it's easy to imagine that installing a water softener is quite complicated. In reality, the installation is fairly straightforward, provided you have the plumbing skills required to make the various water supply connections. It's regarded as an advanced-level project for that reason. You will likely be cutting into plumbing pipes to insert the water softener into the water supply system, and this may require using a propane torch to solder copper pipes and fittings. If you're not experienced at this type of work, it is better to have the water softener installed by a plumber or water softener service that specializes in this work.

Installing a water softener will be easier if you understand precisely how a water softener works. Some research on the different types of water softeners and how they function is a good idea.

The project demonstrated here shows how to install the most popular type of water softener, an ion-exchange system that uses a brine tank with salt or potassium pellets to provide the backwash solution. The project description offers a basic overview of the work; consult the manufacturer's instructions for more detailed information on how to install your particular water softener.


This project requires more than just basic DIY knowledge. The cost of this project can cost up to $10,000 since there's multiple trades involved. When a project requires this kind of investment, designating it to a professional is often the best route.

What You'll Need

Equipment / Tools

  • Adjustable wrench
  • Channel-lock pliers
  • Hacksaw (if needed)
  • Propane torch (if needed)
  • Screwdriver


  • Water softener with bypass valve
  • Plumbing pipe fittings (as needed)
  • Flexible supply tubes
  • Solder and flux (if needed)
  • 1/2-inch diameter flexible drain tubing
  • Pipe clamps
  • Air gap fitting (if needed)


Materials and tools to install a water softener

The Spruce / Kevin Norris

  1. Install the Bypass Valve

    If desired, you can install a bypass valve onto the water softener unit. Some water softeners include a bypass valve that allows you to shut off the water going through the water softener in the event that repairs or temporary shut-off is needed.

    Push the bypass valve into place on the back of the unit. Secure the valve by using the clips provided.

    Bypass valve installed on top of water softener unit

    The Spruce / Kevin Norris

  2. Tie Into the Water Supply

    A water softener can be hard-piped into the water supply system, or it can be tied in using flexible supply tubes, similar to the way that water heaters are usually connected. Flexible supply tubes are normally the better solution since they make it easy to remove or bypass the system in the future.

    To connect the water heater using flexible supply tubes, first shut off the water to your home and drain the pipes. Cut out a section of the water supply line and install adapters to accept the flex tube fittings. The type of adapters you use will depend on what type of water supply pipes are used in your home. With traditional copper water pipes, the adapter fittings are usually soldered on, or you can use push-fit fittings that don’t require soldering.

    Connect the flex lines to the water supply pipes, then into the back of the water softener unit, as directed by the manufacturer. Make sure the supply-side pipe is connected to the inlet port on the water softener; the house-side pipe to the outlet port. Tighten the fittings using an adjustable wrench or channel-lock pliers.

    Section of copper water supply tube cut with hacksaw

    The Spruce / Kevin Norris

  3. Connect Tubing Between Tanks

    If your water softener has two separate tanks that stand apart, connect the brine tank and the mineral tank with the tubing included with the water softener. With most water softeners, the tubes are secured with hose clamps.

    Brine and mineral tank tubing connected to water softener unit

    The Spruce / Kevin Norris

  4. Connect the Drain Tubes

    Most water softeners require two drain tubes. One of the drain tubes connects to the control valve and is used to void the backwash water during the regeneration cycle. The other drain tube connects to the brine tank and serves as an overflow drain. Both lines then run to the home drain, but they should not be connected together.

    There are various options to accomplish the drain requirements. Often, the drain lines are run to a floor drain, but you can also extend the drain line into the standpipe that also drains a washing machine, or into a utility sink or sump pit.

    In most communities, it is illegal to connect the water softener drain directly to the home drain system without an air gap. Similar to the requirement for dishwashers, the drain line needs an air gap fitting designed to prevent back-siphoning of contaminated drain water into the water softener. There are special air gap fittings that allow you to connect the water softener's drain tubes directly to a drainpipe or standpipe.

    In our example, the owner has installed a dedicated drain pipe with a trap, into which they have run the two drain tubes for the water softener. A slight separation between the drain tubes and the drain pipe provides the required air gap.

    To connect the drain tubes, attach a length of 1/2-inch (inside diameter) flexible tubing to the drain elbows on both the control valve and the brine tank, using hose clamps, and run the tubes to the selected drain location. Attach them to an air gap fitting if you are using one, or anchor them securely to a utility sink or floor drain.

    Drain tubes connected to water softener and control valve

    The Spruce / Kevin Norris

  5. Start the System

    Turn on the home's water supply system by opening the main shutoff valve. Filing the water supply system needs to be done slowly, since sudden pressure can damage fittings. Open a cold water tap somewhere in the house to allow air to escape as you refill the pipes.

    Next, follow the start-up steps for your water softener, which will include plugging in the appliance, then setting the time of day and the water hardness level. The final step is to add the salt (or potassium chloride) and start the system. Read the manufacturer's recommendations about what type and quantity of salt or potassium chloride to use.

    Main shutoff valve lever being turned to turn water supply on

    The Spruce / Kevin Norris

  6. Run a Backwash Cycle

    Follow the manufacturer's instructions for running a backwash (regeneration) cycle on the water softener. This process purges air from the system and loosens the plastic resin beads in the mineral tank to ensure that the system will run efficiently. Check for leaks during the backwash cycle. When it is complete, check the water level in the brine tank and make whatever adjustments are recommended by the manufacturer.

    Water softener checked for leaks

    The Spruce / Kevin Norris