Water hardness is measured by the concentration of calcium and magnesium minerals in your water, typically expressed in grains per gallon (gpg), milligrams per liter (mg/L) or parts per million (ppm). These measurements show whether your water is soft, hard or somewhere in between.
Hard water is one of the most common water quality issues homeowners face, often leaving mineral buildup on fixtures, spots on dishes and residue that can dry out skin and hair. But before you can measure and address hard water, it’s helpful to understand what water hardness actually means and how it affects your home.
What Is Water Hardness?
Water hardness refers to the amount of dissolved calcium and magnesium minerals in your water supply. These hardness minerals naturally accumulate when water flows through rocks and soil that contains these minerals, like limestone. The higher the mineral content, the harder your water becomes.
Hard water is generally not a health risk for drinking water, but it can cause issues around your home — like scale buildup on plumbing fixtures, mineral deposits in water-using appliances, spotty dishes, and dry skin and hair after bathing.
Water Hardness Levels: How Is Water Hardness Measured?
Water hardness is often measured in grains per gallon of calcium carbonate, milligrams per liter or parts per million, which are equivalent. The scales are as follows:
- Soft: 0-3.5 gpg / 0-60 mg/L or ppm
- Moderately hard: 3.6-7.0 gpg / 61-120 mg/L or ppm
- Hard: 7.1-17.5 gpg / 121-300 mg/L or ppm
- Very hard: Over 17.5 gpg / over 300 mg/L or ppm
The scales above are based on information from Montana State University, though various sources list these categories with slightly different measurements. For instance, this water hardness scale used by Health Canada breaks down results in mg/L 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
To use the same gpg 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.
How To Test for Water Hardness
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 water quality 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 specific data on this topic. Plus, hardness is not only determined by the source of your water; it also can accumulate more hardness minerals as it travels to your taps. This means that even in the same neighborhood, water hardness levels can even vary from home to home.
[EMBED HARD WATER GUIDE]
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. In-home and IL EPA-certified 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 also understand how to interpret them and what steps to take next.
Schedule your free water test.
Choosing the Right Water Softener
If you do 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, how much water you use and other factors, 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.
