Water with calcium and magnesium levels at or above 120 ppm (parts per million) is generally considered hard water. However, the precise definition can vary slightly depending on the source. Some sources define slightly hard water as 60-120 ppm, while others consider anything above 75 ppm as hard. Very hard water can have levels exceeding 200 ppm or even 700 ppm.
Understanding Water Hardness
Water hardness is measured by the concentration of dissolved minerals, primarily calcium and magnesium carbonates. These minerals aren't harmful to your health but can cause issues with appliances and leave behind limescale deposits.
- Soft Water: Generally less than 60 ppm.
- Slightly Hard Water: 60-120 ppm (some sources define this range as 17-60 ppm or up to 75 ppm).
- Moderately Hard Water: 121-180 ppm (some sources may use a different range).
- Hard Water: 120 ppm and above (some sources define this as 75 ppm and above).
- Very Hard Water: 200 ppm and above (some sources indicate this may reach 700 ppm).
The U.S. Department of Energy states that water with calcium or magnesium levels at or above 7 grains per gallon (GPG), which equates to 120 ppm, officially qualifies as hard water. Understanding and Dealing With Hard Water - Department of Energy Other sources offer slightly different ranges, but 120 ppm serves as a common threshold.
Practical Implications
Knowing your water's hardness level is crucial for several reasons:
- Appliance Maintenance: Hard water can damage appliances like water heaters and washing machines by building up scale.
- Cleaning: Hard water reduces the effectiveness of soaps and detergents, requiring more to achieve the same results.
- Water Softeners: If your water hardness exceeds recommended levels, a water softener might be necessary to mitigate issues.
