How is hard water measured?
Hard water is measured in parts per million (PPM) and how many particles of hardness are dissolved in the water per million particles gives a rating. This rating has been developed over time to the following categories.
| 0-50 PPM | Is soft |
| 51-100 PPM | Is moderately soft |
| 101 - 150 PPM | Is slightly hard |
| 151 - 200 PPM | Is moderately hard |
| 201 - 275 PPM | Is hard |
| 276 - 350 PPM | Is very hard |
| 350+ PPM | Is agressively hard |