How to Measure Water Hardness

Water hardness levels are measured in grains per gallon (gpg) of calcium carbonate. Less than 3.5 gpg is soft, between 3.6 and 7.0 is moderately hard, between 7.1 and 17.5 is hard and anything over that is very hard. Hard water symptoms like limescale, spotty dishes, reduced water pressure and dry skin vary in severity depending on these hardness levels.

Measuring water hardness can help you determine what kind of water softener will best meet your needs. To prepare for the next steps to soft water, learn how to assess your water hardness, understand the results and apply your findings.

Testing for Water Hardness

Hard water is typically a result of high concentrations of dissolved minerals, mainly calcium and magnesium, in your water supply. Depending on the source of your water, you may be more or less likely to have hard water problems, and well water users are particularly susceptible to this issue.

Check With Your Water Supplier

This isn’t an option for households that use well water, but if you have city water and you suspect you may have problems with hardness, you might want to contact your supplier as a first step.

Your local water supplier’s website and annual report are good places to begin acquiring information about general water hardness levels in your area. However, the information included in annual reports varies by location, so your supplier may not provide data on this topic. Even if relevant information is available, it will apply broadly to hardness levels in your area. The results won’t tell you how hard the water is in your household.

Noticing hard water symptoms and other potential issues with your water? Find out what’s going on and how to fix it – try our Water Solutions Finder.

Try a DIY Hard Water Test

Determining whether or not you have water hardness doesn’t have to be complicated. One quick way to check is by looking for visible limescale buildup around faucets, showerheads and sinks.

Alternatively, you can conduct a simple at-home test with just a clear bottle and a few drops of pure liquid soap. Here’s how to check your water:

Fill the bottle one-third full with tap water.
Add a few drops of the liquid soap.
Close the lid and shake vigorously for 5–10 seconds.

If the water forms fluffy bubbles and looks mostly clear, your water is likely soft. On the other hand, if the water looks cloudy, milky or produces very few suds, you may have hard water.

This method doesn’t give exact hardness levels, but it’s a helpful first step.

Get Your Home’s Water Tested

To find out about the specific hardness levels in your home water supply currently, you’ll have to conduct testing.

There are a variety of different home testing kits available for determining the relative concentration of hardness minerals in your home water supply. Home and lab testing options are available from water treatment professionals like Culligan, too. Working with a water treatment company can help ensure that you not only get the most accurate results but understand how to interpret them and what steps to take next.

Schedule a Water Test with Culligan Today!

 Water Hardness Levels: How Is Water Hardness Measured?

To measure water hardness, you need to know the grains of calcium carbonate in each gallon of water (gpg) or the milligrams per liter (mg/L). The scales are as follows:

• Soft: 0-3.5 gpg / 0-60 mg/L
• Moderately hard: 3.6-7.0 gpg / 61-120 mg/L
• Hard: 7.1-17.5 gpg / 121-300 mg/L
• Very hard: Over 17.5 gpg / over 300 mg/L

These scales are based on information from Montana State University. Various sources list these categories with slightly different measurements.

Parts per Million and Milligrams per Liter

Often, water hardness test results will be delivered in ppm or mg/L, which are equivalent.

To use the same hardness scale above, you can simply convert your ppm or mg/L by dividing that number by 17.1 to find the gpg equivalent. So, for example, 130 mg/L or ppm would be 7.6 gpg, which is considered hard water.

For a quick reference, this water hardness scale used by Health Canada, breaks down results in mg/L and ppm as follows:

• Less than 60 mg/L is considered soft
• Between 60 and 120 mg/L is considered medium hard
• Between 120 and 180 mg/L is considered hard
• More than 180 mg/L is considered very hard

Using the Water Hardness Scale for Water Softener Selection

If you do notice that you have hard water, a water softener can help rid your home of issues like limescale buildup, dry hair and skin, spotty dishes and inefficiency of water-using appliances.

With a reliable water hardness test and information about your household water usage, you’ll be able to work with a professional to determine what kind of water softener will best suit your needs. Based on where your home water supply falls on the hardness scale, as well as your family’s softness preference and how much water they use, you can choose the best water softener that suits your requirements.

Take Action Against Hard Water

Hard water isn’t something you just have to put up with. If you notice any of the troubling signs, from clogged pipes to a filmy residue on your hair or skin after showering, make sure to measure the hardness level of your home water supply.

Once you know where you stand, you can find appropriate solutions to meet your household’s needs. Industry professionals, like your local Culligan expert, can help you conduct testing and find a water softener system that’s right for you.

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