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What is Hard Water?
the effects of water hardness on your body and home
Hard water is water that has high mineral content. It is formed when water filters through deposits of limestone, chalk, or gypsum which are largely made up of calcium and magnesium carbonates, bicarbonates, and sulfates.
Hard water is high in dissolved minerals, largely calcium and magnesium. The level of hardness is determined by the amount of these dissolved minerals that can be detected. In hard water, soap reacts with the calcium to form "soap scum."
Hardness can be found in both types of water, municipal and well. It can range from slightly hard to extremely hard water.
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At Pentair, we take water quality seriously. That's why we've invested in state-of-the-art water quality labs staffed by a team of highly trained specialists. Our labs are equipped with the latest technologies, allowing us to conduct a wide range of tests for all kinds of applications.
Measuring Hardness
Measuring Hardness
The grain per gallon (GPG) is a unit of water hardness defined as 1 grain (64.8 milligrams) of calcium carbonate dissolved in 1 US gallon of water (3.79 L). This is 1 part in about 58,000 parts of water or 17.1 parts per million (ppm).
For a good comparison of the relative weight and size of a grain, one standard aspirin tablet usually weighs 5 grains. You can download this chart for your reference.
| Water Hardness Description | Grains Per Gallon (GPG) | Parts Per Million (PPM) |
| Soft Water | Less than 1.0 | Less than 17.1 |
| Slightly Hard | 1.0 to 3.5 | 17.1 to 60.0 |
| Moderately Hard | 3.5 to 7.0 | 60.0 to 120.0 |
| Hard Water | 7.0 to 10.5 | 120.0 to 180.0 |
| Very Hard | 10.5 and over | 180.0 and over |
Effects of hard water
Hard water can have a negative effect on our home goods, cleansers, and body.
Limiting Cleaning Power
Hard water reacts negatively to soaps and detergents. Instead of creating a rich and foamy lather, it forms a substance that is curdy. More soap and detergent are necessary to overcome the negative effects of hard water.
Need Help?
Treat water confidently with reliable and industry proven Pentair water softening solutions. A legacy of quality and reliability and a wide range of solutions for your application make Pentair your go-to choice for water softening.
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What's in your water?
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