Water hardness is measured using specific units to quantify the concentration of minerals, primarily calcium and magnesium, present in the water. Two common measurement units are used: grains per gallon (gpg) and parts per million (ppm).
Understanding Measurement Units
Here's a breakdown of the two primary measurements used to assess water hardness:
Grains Per Gallon (gpg)
- Definition: Grains per gallon originated from the practice of using the weight of a dry wheat kernel as a reference.
- Significance: It's an older unit of measurement, but still used in some regions.
- Equivalence: According to the Encyclopaedia Britannica, one grain per gallon is approximately equal to 1/7000 of a pound.
Parts Per Million (ppm)
- Definition: Parts per million is a more universally used measurement expressing the amount of a substance per million parts of water.
Hardness Level Classification
While the reference does not classify the hardness levels, generally, water hardness is categorized as follows based on ppm:
| Hardness Level | ppm (mg/L) |
|---|---|
| Soft | 0-60 |
| Moderately Hard | 61-120 |
| Hard | 121-180 |
| Very Hard | 180+ |
These classifications help understand the level of mineral concentration in the water and its potential impact on plumbing, appliances, and even taste.
