Hard water spots are caused when water with a high calcium carbonate content evaporates. The calcium remains behind, and is the cause of the white spots. Hard water is classified as water with a one milligram of calcium carbonate per liter of water. This is sometimes referred to as one degree American, or one part per million. Hard water is naturally occurring and is typically found is mountainous areas or locations with a low water table.
Hard water has a high mineral content, comprised of calcium, magnesium, metal ions. It can also include biocarbonates and sulfates. The calcium is often in the form of limestone, chalk, or calcium sulfate. The most common source of magnesium is dolomite and metal ions can be derived from metal water pipes.
Many people report water spots on dishes removed from the dishwater, but not on dished washed by hand. Very hot water will result in an increased volume of water spots. An increased number of spots are created with the use of hot water and high heat drying.
To reduce hot water spots, water softener can be added to the hot water heater. These salt-based pucks are added every 30 to 60 days and dissolve slowly in the water tank. They are used to neutralize the salt through a simple, chemical reaction.
An ion exchange column can also be used. This unit is installed in the water heater and is reusable. The calcium and magnesium ions are attracted to the column. They bond to the column, releasing sodium ions. In time, the column becomes filled with calcium ions and must be flushed with water to refresh the ions. Once this is done, it can be replaced in the water heater.
Reduce the temperature of your dishwasher water to reduce the volume of hard water spots and flush the metal pipes to remove salt buildup that occurs naturally over time. Glass spot removers can also be purchased to remove these spots.
The most effective method of removing hard water spots is to dry dishes and glasses by hand. Once they are dry, the water cannot evaporate, leaving spots. Spots on shower doors are hard to remove, as they are often combined with soap residue.
There is a wide range of specific cleaning products available, designed to remove hard water spots. A low cost method of removing hard water spots from your shower doors is to wipe down the shower walls after use. This reduces the moisture on the wall, and therefore the water spots.