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Water Hardness

Water Hardness


As water moves through soil and rock, it dissolves very small amounts of minerals and holds them into solution. Calcium and magnesium dissolved in water are the most common minerals that make water hard. The higher the concentration of these minerals the harder the water. Hard water is not a health hazard but does interfere with many common household tasks.

Identifying Hard Water

You can usually detect hard water by the evidence in your home, including:

  • Soap scum on bathtubs, shower tiles, and basins
  • Film left on the body resulting in dry skin and dull, limp hair
  • Decreased sudsing and cleaning capabilities of soaps and detergents, resulting in dingy laundry and reduced life of
  • Increased buildup of scale on plumbing fixtures and cooking utensils such as a tea kettle, coffee maker, pasta pot, and dish
  • Clogged pipes or appliances resulting in reduced water flow and increased repairs

Hardness Classification

Hardness is measured in grains per gallon of water or milligrams per liter. Grains per gallon (gpg) is a unit of weight for a volume of water, as is milligrams per liter (mg/l). One gpg (1 gpg) is equivalent to 17.1 mg/l. You can evaluate the hardness of your water supply by referring to the following chart.





0 - 17.1

0 - 1

Slightly hard

17.1 - 60

1 - 3.5

Moderately hard

60 - 120

3.5 - 7.0


120 - 180

7.0 - 10.5

Very Hard

180 & over

10.5 & over

Although the measurable level of hardness will fluctuate over the year as sources of water supply are interchanged depending on demand, the City of Fullerton is generally considered to have “very hard water”. Fullerton’s most recent Water Quality Report indicates that Fullerton water ranges in hardness from 14 to 25 grains per gallon.

Removing Hardness

This is a matter of personal choice. Hard water is safe to drink.While the calcium and magnesium minerals are important to good health, they may cause white spots or a white film on your glassware, coffee pots and shower doors, as well as deposits in boilers and water heaters.These spots or deposits are formed when hard water is heated or evaporates.It is best to read the owner’s manual for your dishwasher and follow the manufacturer’s recommendations regarding settings for hard water.Some other tips that may help reduce spotting include using hotter water, varying the brand and type of rinse agent and detergent, and adding white vinegar to the rinse cycle of the dishwasher.

There are treatment options available to consumers that can remove or lower the hardness from water. Treatment will improve the efficiency and life of appliances using hot water. The most common method to treat hard water is through ion exchange water softening. Ion exchange water softening is a process in which the hardness ions (magnesium and calcium) are exchanged with either sodium or occasionally, potassium ions. This is accomplished by directing the flow of hard water over a bed of plastic resin beads. Each bead has a slight electric charge, which holds the sodium on the bead. As the water flows over the beads, the hardness minerals (ions) are attracted to the beads. When the hardness minerals attach themselves to the beads, the sodium ions are displaced. Hence, the hardness ions are replaced by the sodium ions.

As some point the plastic resin beads will be covered with hardness ions and will no longer be able to remove hardness from the water. In order to remove the hardness ions from the beads, a brine or salt (sodium chloride) solution is added to the resin bed. This solution contains a high concentration of sodium ions, which remove the hardness ions from the beads. Next the solution and the hardness ions are flushed out of the resin bed with fresh water, and once again the beads can remove hardness from the water. This process is called regeneration.

How to Select a Water Softener

There are many different kinds of water softeners available. Before purchasing a water softener you should make sure that the unit has sufficient water softening capacity for your family. A typical person uses 100 gallons of water per day.

Another important feature to consider is how the equipment initiates the regeneration process. Water softening equipment uses three general methods of controlling water softener regeneration:

  • time clock
  • demand initiated regeneration
  • metered

Of these three methods, demand initiated regeneration is considered to be by far the most efficient method of regeneration. Both this method and the metered method offer savings in salt and water usage over the time clock method.

Other important factors to consider are the warranty and the reputation of the manufacturer. Consumers can check with the Better Business Bureau for references and complaints.

Health Related Concerns Associated with Softened Water

Softening of water with a common water softener does increase the sodium content in the water. Therefore, if you have health concerns about your sodium intake, consult your physician. Although the minerals that make up hard water can provide trace amount of nutritional benefit for good health, the concentration of the minerals present do affect the "taste" of water. Normally, water softeners are connected to the piping feeding the hot water heater to ensure the hot water is the only water softened in the home. This reduces the hardness in your hot water, while enabling you to use un-softened water for cooking, cleaning and drinking.

Additional Questions/Comments

Should you have any questions regarding the hardness of your water, please contact the Water Quality Specialist for the City of Fullerton at (714) 738-2835.