How to Test for Hard Water

Black shower head with running water testing for hard water

The Spruce / Sarah Lee

Project Overview
  • Working Time: 15 mins
  • Total Time: 15 mins
  • Skill Level: Kid-friendly

Hardness is one of the most common complaints homeowners have about their water quality. Hard water typically contains relatively high levels of magnesium and calcium, along with other natural minerals and metals. Hard water is not a health concern, but it can lead to excessive scale buildup in water pipes, boilers, hot-water heating systems, and other equipment that uses water. An even bigger nuisance to most homeowners is the fact the hard water does not clean laundry or dishes as well as soft water, and it requires more soap or shampoo to create suds. 

There are several ways to test for hard water. The most accurate test is done through an independent laboratory, using a sample you provide, but a comprehensive water test can be expensive and can take a while for results. For fast and inexpensive—if less precise—results, try one of the methods below to get a rough estimate of your water's hardness.

What You'll Need

Equipment / Tools

  • Clear bottle with cap


  • Liquid dishwashing soap


Large clear bottle with water and soap suds in front of liquid dishwashing soap bottle

The Spruce / Sarah Lee


Soapsuds Test

  1. Prepare the Bottle

    Find a clean glass or plastic bottle with a tight-fitting cap. Fill the bottle 1/3 full with water straight from the faucet (should be about 8 to 10 ounces). 

    Glass jar being filled with water in kitchen sink

    The Spruce / Sarah Lee

  2. Add Dishwashing Liquid

    Add 10 drops of ​dishwashing liquid; use pure liquid soap, not "detergent," and shake well for at least 10 seconds. Set the bottle down and observe the results. 

    Dishwashing liquid added to glass jar with water

    The Spruce / Sarah Lee

  3. Determine the Results

    If the soapy solution foams up quickly, creating a lot of suds, and the water below the suds layer is relatively clear, you probably have at least fairly soft water. 

    However, if the solution does not foam up well, creating only a shallow layer of suds, and the water below the suds is cloudy, you likely have hard water. 

    Large clear jar with water and soap suds to test for hard water

    The Spruce / Sarah Lee

    DIY Test Kit

    Home test kits for water quality are sold in home improvement and hardware stores and through many online retailers. Look for a kit made by a reputable water-testing manufacturer, and make sure the kit tests for hardness. Some kits test only for specific contaminants, like radon, while others test for overall quality and safety. 

    Home test kit strip with colored markings to test for hard water near glass container

    The Spruce / Sarah Lee

    One of the simplest tests to perform is a wet-strip test, similar to a test for swimming pool or spa water. You fill a container with tap water, immerse the paper test strip in the water, then compare the resulting color of the strip with the kit's chart. The instructions will tell you how hard your water is based on the result. 

    Run the Numbers

    If your house is on the city or municipal water supply, you can call the water utility and ask for their latest water quality report. Many utilities also post reports online. These reports can be very technical, and they don't necessarily reflect the water quality directly at your tap because the water is tested as it leaves the treatment facility, and water can pick up minerals from the piping en route to your house. However, water quality reports can provide an idea of the water hardness in your area.

    Water hardness is commonly reported in milligrams per liter (mg/L) as calcium carbonate. Note the value of calcium carbonate in the report and compare it to the following scale used by the U.S. Geological Survey

    • Soft water: 0-60 mg/L
    • Moderately hard water: 61-120 mg/L
    • Hard water: 121-180 mg/L
    • Very hard water: Over 180 mg/L

    Dealing With Hard Water

    As mentioned, hard water doesn't pose a health risk. In fact, some studies have even shown that the calcium and magnesium in hard water might help combat cardiovascular disease and certain cancers. That being said, not everyone appreciates the taste of hard water—or the filmy residue it can leave on shower walls and glasses in the dishwasher. Hard water can also clog showerheads and build up scale in appliances like coffee makers and water heaters, reducing their efficiency. In addition, it can create limp, brittle hair and dry skin as it isn't as effective at rinsing soap away as soft water.

    So, what can you do?

    The most obvious, although sometimes quite pricey, solution is to install a whole-home water softener. This is typically installed just after the main water line that enters your house and uses special salts to counteract the calcium and magnesium. However, you could also install a softener on the outgoing line from your hot water heater if you only want to soften the hot water in your home which is something you might want to do if you want to continue drinking hard water, but you'd prefer to shower with hot water.

    If you don't want to use a whole-home softening system, you can also go a much cheaper route and use vinegar. It's an effective scale fighter and can be used to clean hard-water residue off counters, fixtures, and shower walls, as well as unclog showerheads. You can also run it through your coffee maker to descale it, and even put 1/2 to 1 cup in your washing machine during the rinse cycle to lower the water's pH, making the minerals more soluble and keeping your clothes free of mineral buildup.