How to Test Your Well Water for Hardness
Water hardness measures dissolved calcium and magnesium. Testing tells you where you fall on the USGS hardness scale and whether softening makes sense.
Quick Answer
Hardness measures dissolved calcium and magnesium in your water. It is an aesthetic and plumbing issue, not a health risk. Using the USGS scale, water is soft below 60 mg/L, moderately hard at 61 to 120, hard at 121 to 180, and very hard above 180 mg/L as calcium carbonate.
What hardness does
Hard water is extremely common in wells because groundwater picks up minerals from rock. It causes scale in pipes and water heaters, soap scum, spotting on dishes, and dull laundry. It is not harmful to drink, which is why hardness is not a health-based standard.
| Classification | Hardness (mg/L as CaCO3) |
|---|---|
| Soft | Less than 60 |
| Moderately hard | 61 to 120 |
| Hard | 121 to 180 |
| Very hard | Greater than 180 |
How to test hardness
- 1Collect a sample and send it to a laboratory, or use a titration test kit for a quick estimate.
- 2Note the units reported, usually mg/L as calcium carbonate or grains per gallon (1 grain per gallon is about 17.1 mg/L).
- 3Compare your result to the USGS bands above.
- 4If you are considering a softener, use the result to size the system correctly.
Hardness is not a safety test
Frequently asked questions
- Do I need to soften hard water?
- Softening is optional and based on preference and plumbing protection, not health. Many people soften very hard water to reduce scale, but it is not required for safety.
Sources & references
- Hardness of Water — USGS, accessed October 29, 2026
- Secondary Drinking Water Standards: Guidance for Nuisance Chemicals — US EPA, accessed October 29, 2026
This guide is documentary research and general information, not a laboratory analysis or professional assessment of your specific well. See our disclaimer.