How to Understand Water Hardness Test Results

Water described as "hard" is high in dissolved minerals, specifically calcium and magnesium.

Hard water is not a health hazard, but dealing with hard water in the home can be a nuisance. Laundry can become stiff, water vases encrusted with minerals, and bathing in hard water can leave a sticky film on the skin. The hardness (calcium and magnesium concentration) of water can be tested with a water testing kit. Water hardness is more accurately tested with a laboratory test. Water hardness can be managed with packaged water softeners or with a mechanical ion exchange softening unit.

Things You'll Need

• Water test kit

Instructions

How to Interpret Water Hardness Test Results

1. Acquire a water hardness testing kit from a testing supply company. Follow the directions on the water hardness testing kit.

2. Read the results. The hardness of your water will be reported in grains per gallon, milligrams per liter (mg/l) or parts per million (ppm). One grain of hardness equals 17.1 mg/l or ppm of hardness.

3. Interpret the results. water hardness is classified by the U.S. Department of Interior and the Water Quality Association as follows:

   Soft : 0 - 1 grains/gal

   Slightly hard: 1 - 3.5 grains/gal

   Moderately hard: 3.5 - 7.0 grains/gal

   Hard: 7.0 - 10.5 grains/gal

   Very Hard: 10.5 grains/gal & over

4. Assess your options. If your water has a water hardness of 7.0 grains/gal or more, you may want to soften it. There are two ways to soften your water: packaged water softeners and mechanical water softening units.

Tips & Warnings

• Softened water is not recommended for watering plants, lawns, and gardens because of its sodium content.

References

• Water-Research.net: Hard Water Results

Resources

• Water-Research.net: Hard Water Results