The hardness of water is related to the amount of dissolved calcium and magnesium it naturally contains. The higher the amount of minerals, the harder the water. Signs of hard water include spots or a film on dishes and residue on clothing. You may notice that you need to use more detergent, soap, or shampoo. Hard water can also cause mineral buildup in pipes and mechanical equipment.
While there are no harmful health effects from these minerals in the water, some homeowners choose to use a water softener to reduce the hardness.
If you have a water softener, we suggest setting the softener between 10-17 grains per gallon with iron levels up to 1 mg/L. Otsego’s municipal water supply has an average hardness level of 15 grains per gallon. If the water feels too "slimy," turn the softener down in small increments until you reach the desired softness. Water that is over softened may become corrosive.
MN Pollution Control Agency (MPCA)
University of MN Water Softening