What is the hardness of my water?
Hardness levels in Maine waters are generally low but can range from near zero to several hundred milligrams per liter as calcium carbonate (mg/L as CaCO3), the standard unit for hardness. The Greater Portland water source (Sebago Lake) has a hardness value of 9 and is described as soft, as you can see from the following table.
| Hardness Range (mg/L as CaCO3) | Description |
| 0 – 75 | Soft |
| 75 – 150 | Moderately hard |
| 150 – 300 | Hard |
| More than 300 | Very hard |
The term “hard water” does not have a precise definition but is usually used to describe water which does not lather well when soap is added or which forms a scale inside hot water heaters. These problems are caused by high concentrations of the naturally occurring elements calcium and magnesium which depends largely on the local bedrock.
While there are no health-related regulations pertaining to drinking water hardness, a value below 100 mg/L is ideal for ordinary domestic purposes. Therefore, water softening for our residential customers is not necessary.