With more than 30 years’ experience in the residential and commercial water treatment space, Mark Nelson is a Class 1 Drinking-Water Operator and a CBWA (Canadian Bottled Water Association) Certified Plant Operator. As founder and president of Nelson Water in Ottawa, Mark focuses on dealing with challenging water treatment system designs for problem water. He also heads the largest water bottling plant in the city of Ottawa with a delivery network throughout the Valley.

If you’ve noticed that your soap doesn’t lather, a buildup of soap scum on shower doors, and limescale on plumbing fixtures you have hard water. But, there are varying degrees of hardness depending on a number of factors, including the local area, geographical features, nearby mineral deposits, and more. The only tried and tested method to remove hardness from water is to install a water softener system in your home. To determine the kind of water softener you need, it’s important to assess the water hardness and apply those results to your choices. In this article, we will take a closer look at what water hardness is, how it’s tested and how you can use that information.

What is Water Hardness?

Water is categorized as hard when it has a higher than normal concentration of certain dissolved minerals. The main culprits are calcium, magnesium, and to a certain extent, iron. These dissolved minerals are not removed at the municipal water treatment plant. Both private well and public water users can receive a supply of hard water at their taps. In fact, private well water users are slightly more prone to hard water problems due to groundwater issues. It’s estimated that almost 90% of U.S. homes are supplied with hard water and this is why many people install a water softener.

Check with the Local Water Supplier

The first step for public water users is to check the website of their local water supplier. There should be an annual report that you can read and download for later reference. This report contains a wealth of information on the quality and hardness of the water in your local area. The details can vary depending on the location and in some cases there may be less data related to this particular topic. Even if you do have water hardness information, it will be pretty general and it may not be specific to your household. The only way to obtain accurate data on the hardness of your water supply is water resting.

How to Test Your Water Hardness

There are a number of different home testing kits that are designed to determine the concentration of dissolved mineral content in water. There are home testing kits and those are sent away to a laboratory where they are analyzed by water treatment experts. But, the best way to get a personalized service and accurate results is to work with a local water treatment company. They will understand the local water conditions, they can conduct the testing and they will know how to interpret the results.

Understanding Water Hardness Measurements

At first glance, you may believe that it’s hard to understand or interpret water test results. A certain degree of familiarity with water hardness measurement scales can be useful. Like any complex topic, there are certain terms that need to be understood to fully grasp the context. Most water test findings will be delivered in the form of numbers that report the concentration of calcium carbonate to the equivalents for a specific unit of water. The testing results are usually expressed in parts per million (ppm), grains per gallon (gpg), or milligrams per liter (mg/L). Let’s break down how these expressions can be understood and applied to a useful hard water summary.

Grains per Gallon (gpg)

On the water hardness scale, the measurement of calcium carbonate can be expressed as gpg. As the name suggests, this is how many grains of calcium carbonate that would be found in 1 gallon of water. The higher this number, the harder the water will be and this is easier to grasp with the following widely accepted benchmarks:

  • Less than 1 gpg: this is considered to be soft water.
  • 1 – 3.5 gpg: this is considered to be slightly hard water.
  • 5 – 7 gpg: this is considered to be moderately hard water.
  • 7 – 10.5 gpg: this is considered to be hard water.
  • 5 gpg or more: this is considered to be very hard.

Parts per Million (ppm) and Milligrams per Liter (mg/L)

In some cases, the water hardness test results are delivered in ppm or mg/L. We are covering these two hardness scales together because they are equivalent and easy to convert from gpg which we covered earlier.

To find the equivalent on the hardness scale above, simply take the ppm or mg/L value and divide it by 17.1 to find the number in gpg. As an example: the water test shows a hardness value of 130 ppm or mg/L which would be 7.6 gpg on our scale or hard water. The formula in this case would be 130/17.1=7.6.

For faster reference and to make this water hardness scale even easier to use, we have converted the above scale to ppm and mg/L.

  • Less than 60 mg/L: this is considered to be soft water.
  • 60 – 120 mg/L: this is considered to be medium hard water.
  • 120 – 180 mg/L: this is considered to be hard water.
  • More than 180 mg/L: this is considered to be very hard water.

Selecting a Water Softener for Your Home

Now that you have an understanding of how to interpret the test results and how they relate to water hardness scales, it’s easier to make informed choices. Hard water can cause a number of problems in the home and these will not go away unless the core issue is fixed. The most reliable water softening method uses an ion-exchange process to swap mineral ions for more benign sodium or potassium (salt) ions. A water softener needs to be matched carefully to your home to ensure that it meets your needs without wasting water. If you have a problem with higher concentrations of iron, there are water softeners that can remove it or you may need a dedicated iron filter.

The best way to choose the correct water softener is to work with a local water treatment specialist.