High concentrations of calcium and magnesium in water interfere with the effectiveness of cleaning products. Hard water increases films and stains from soaps, minerals and other pollutants. Bathroom fixtures, sinks, washers, dishwashers and other surfaces in contact with water will require more frequent cleaning if one has hard water. Other water nuisances include some of the following. Acidic water tends to be destructive to plumbing and equipment dissolving brass and copper plumbing fittings, leaving blue or green stains.
Reddish stains are likely to be iron.
Iron bacteria may create a reddish slime. Manganese produces brownish or blackish stains. Metallic corrosion such as iron, manganese, and copper minerals respond to acidic solutions and to sequestrants in detergents and other products. Soap curds, calcium and magnesium respond to sequestrants which are ingredients in cleaning products that capture and deactivate minerals in water. Minerals are held in solution so that they do not react with other materials to form scum or film.