Most of the water found throughout the United States is “hard.” This means that the water is contaminated with minerals, such as calcium, sulfur, magnesium, iron, lead, and limestone. These minerals are dissolved into water via the ground from nearby rocks or soil. Water hardness is measured by either the number of grains per gallon (GPG) or milligrams per liter (mg/L). According to the Water Quality Association, if your water tests at 1 GPG or less, your water is considered “soft.” If your water tests at 7 GPG or higher, it is considered hard. (See below for more specific GPG numbers for comparison.) Depending on the level of contamination, hard water may be fine for your health and not cause any major problems for you or your home. On the other hand, your water may contain contaminants that are very harmful for your health and your plumbing system, and you may need to consider installing a water purification system.