What Is a Hard Water Analysis?

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  • Written By: Drue Tibbits
  • Edited By: PJP Schroeder
  • Last Modified Date: 12 October 2018
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A hard water analysis is a test that determines the presence and quantity of specific minerals in a water sample. The analysis is helpful for determining water treatment options. Water softeners are appliances that remove dissolved minerals from water. Most water softeners are programmable, with settings matched to the degree of water hardness. The hard water analysis provides this information.

Hard water contains significant amounts of dissolved calcium and magnesium. As rain filters through the ground into the aquifer, the water dissolves and collects minerals. Limestone, commonly found underground, leaches calcium and magnesium into the filtering water. The resulting hard water is not medically harmful, but it cleans less effectively by interfering with the surfactant properties of soap. The dissolved minerals can also cause a buildup of scale, hardened formations of calcium that can damage plumbing and appliances.


Home owners can perform their own hard water analysis tests, or they can send water samples to laboratories for more detailed information. Hard water testing kits use either chemical titration solutions or paper strips chemically treated to react in the presence of calcium and magnesium. The chemical titration test involves adding a small amount of the solution to a water sample and observing any color change. The paper strip test involves dipping a test strip into the water and watching for a color change on the treated area. In both tests, the amount of dissolved minerals is determined by matching the color change to a color chart supplied with the test.

There are several different rating scales used in a hard water analysis. Depending on the facility doing the water test, the hardness is reported in parts per million (ppm), milligrams per liter (mg/L), or grains per gallon (gpg) of dissolved calcium and magnesium. Moderately hard water is 60 to 120 ppm or mg/L. This is equivalent to 3.5 to 7.0 gpg. Very hard water has a hardness rating above 10.5 gpg, or the equivalent 180 ppm or mg/L.

One method of treating hard water is using a water softener. This appliance uses resin beads to remove the dissolved mineral ions, making the water softer. The softener is filled with a brine solution of dissolved sodium. The sodium, or salt, binds to the negatively charged resin beads. As the hard water passes over the beads, the dissolved mineral ions displace the sodium ions, binding to the resin beads and removing the minerals from the water.


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