What is the hardness of the water?
The hardness of the water is normally between 25 to 35 mg/l (milligrams per liter) or ppm (parts per million). Various levels of hardness in terms of calcium carbonate can be described as follows:
Extremely soft to soft 0-45 mg/l
Soft to moderately hard 46-90 mg/l
Moderately hard to hard 91-130 mg/l
Hard to very hard 131-170 mg/l
Very hard to excessively hard 171-250 mg/l
Too hard for ordinary domestic use over 250 mg/l
Note: Most manufacturers of dishwashers maintain that after about 120 mg/l of hardness that some means of softening or removal of hardness should be used to insure no spotting of the dishes.