You evaluate water hardness by measuring the concentration of dissolved minerals, primarily calcium and magnesium, typically expressed as an equivalent amount of calcium carbonate.
Water hardness is a common water quality characteristic that describes the amount of dissolved minerals it contains. While other minerals contribute, calcium and magnesium are the primary culprits. The higher the concentration of these minerals, the harder the water. This measurement is usually reported in milligrams per liter (mg/L), parts per million (ppm), or grains per gallon (gpg).
To determine your water hardness, you generally need to obtain a water quality report or use a home test kit.
Steps to Evaluate Your Water Hardness
- Obtain Your Result: Find the value for calcium carbonate (or sometimes just "total hardness") on your water quality report from your local municipality or laboratory, or perform a test using a home water hardness test kit and note the result. The result will typically be given in mg/L, ppm, or gpg.
- Compare to Scale: Compare your test result to a standard water hardness scale. According to one common method:
Note the value of the calcium carbonate in your water quality report or your test kit results and compare it to the scale below. In short, if your hard water test result is less than one grain per gallon (17.1 mg/L or less), you have soft water. Anything higher than this value indicates hard water.
Water Hardness Scale
Based on the provided reference, here's a simple scale:
| Hardness Level | Measurement (gpg) | Measurement (mg/L or ppm) |
|---|---|---|
| Soft Water | Less than 1 gpg | Less than 17.1 mg/L |
| Hard Water | 1 gpg or Higher | 17.1 mg/L or Higher |
Note: Different organizations (like the Water Quality Association or USGS) may use slightly different ranges for varying levels of hardness (e.g., slightly hard, moderately hard, very hard), but the basic principle of using mineral concentration (as CaCO₃) remains the same.
Practical Insights
- Test Kit Use: Home test kits are convenient for a quick check, but laboratory tests often provide a more precise measurement.
- Regional Differences: Water hardness varies significantly by geographic location, depending on the source water (groundwater vs. surface water) and the geology of the area.
- Impact: Hard water can lead to scale buildup in pipes and appliances, reduce soap effectiveness, and leave spots on dishes. Soft water may feel slick or slimy and could potentially be corrosive in some plumbing systems.
By finding your water's mineral concentration, expressed as calcium carbonate, and comparing it to a standard scale, you can easily evaluate whether your water is considered soft or hard.
