The hardness of water is measured in part per million or in “grains,” with one grain equivalent to 0.064 g of calcium carbonate.Soft water contains 1 – 4 grains per gallon of some organic matter and has no mineral salts.
Hard water contains 11 – 20 grains per gallon. Water may exhibit temporary hardness due to iron or calcium and magnesium bicarbonate ions.
The water may be softened by boiling (soluble bicarbonates precipitate when boiled and leave deposits or scales) and insoluble carbonates may be removed from the water.
Permanently hard water cannot be softened by boiling as it contains either calcium or magnesium sulfates as well as other salts that are no precipitate by boiling.
Permanent hard water may be softened only by the use of chemical softeners.
Hard water exhibits less cleaning effectiveness than soft water due to the formation of insoluble calcium and magnesium salts with soap, which could be prevented by the use of detergents.
Water has a pH of 7, or neutral; tap water displays a variance on either side of neutral. It may be slightly alkaline or slightly acidic depending on the source and so forth.
Hard water has a pH of up to 8.5. Chlorinated water is that which has had chlorine added to kill or inhibit the growth of microorganisms.
Manufacturing or processing plants may require chemically pure water to prevent turbidity, off color and off flavor. Tap water may not be sufficiently pure for use in food products.
Water Hardness and Treatments
