What Is Hardness?
Sources of Hardness Minerals in Drinking WaterWater is a good solvent and picks up impurities easily. Pure water tasteless, colorless, and odorless is often called the universal solvent. When water is combined with carbon dioxide to form very weak carbonic acid, an even better solvent results. As water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. Calcium and magnesium dissolved in water are the two most common minerals that make water "hard."
Indications of Hard WaterHard water interferes with almost every cleaning task from laundering and dishwashing to bathing and personal grooming. Clothes laundered in hard water may look dingy and feel harsh and scratchy. Dishes and glasses may be spotted when dry. Hard water may cause a film on glass shower doors, shower walls, bathtubs, sinks, faucets, etc. Hair washed in hard water may feel sticky and look dull. Water flow may be reduced b deposits in pipes.
Dealing with hard water problems in the home can be a nuisance. The amount of hardness minerals in water affects the amount of soap and detergent necessary for cleaning. Soap used in hard water combines with the minerals to form a sticky soap curd. Some synthetic detergents are less effective in hard water because the active ingredient is partially inactivated by hardness, even though it stays dissolved. Bathing with soap in hard water leaves a film of sticky soap curd on the skin. The film may prevent removal of soil and bacteria. Soap curd interferes with the return of skin to its normal, slightly acid condition, and may lead to irritation. Soap curd on hair may make it dull, lifeless and difficult to manage.
When doing laundry in hard water, soap curds lodge in fabric during washing to make fabric stiff and rough. Incomplete soil removal from laundry causes graying of white fabric and the loss of brightness in colors. A sour odor can develop in clothes. Continuous laundering in hard water can shorten the life of clothes. In addition, soap curds can deposit on dishes, bathtubs and showers, and all water fixtures.
Potential Health EffectsHard water is not a health hazard. In fact, the National Research Council (National Academy of Sciences) states that hard drinking water generally contributes a small amount toward total calcium and magnesium human dietary needs. They further state that in some instances, where dissolved calcium and magnesium are very high, water could be a major contributor of calcium and magnesium to the diet.
Water TestingIf you are on a municipal water system, the water supplier can tell you the hardness level of the water they deliver. If you have a private water supply, you can have the water tested for hardness. Most water testing laboratories offer hardness tests for a fee. Also many companies that sell water treatment equipment offer hardness tests. When using these water tests, be certain you understand the nature of the test, the water condition being measured, and the significance of the test results. An approximate estimate of water hardness can be obtained without the aid of outside testing facilities. Water hardness testing kits are available for purchase through water testing supply companies. If more accurate measurements are needed, contact a testing laboratory.
Mechanical water softening units can be permanently installed into the plumbing system to continuously remove calcium and magnesium. Water softeners operate on the ion exchange process. In this process, water passes through a media bed, usually suffocated polystyrene beads. The beads are supersaturated with sodium. The ion exchange process takes place as hard water passes through the softening material. The hardness minerals attach themselves to the resin beads while sodium on the resin beads is released simultaneously into the water. When the resin becomes saturated with calcium and magnesium, it must be recharged. The recharging is done by passing a salt (brine) solution through the resin. The sodium replaces the calcium and magnesium which are discharged in the waste water. Hard water treated with an ion exchange water softener has sodium added. According to the Water Quality Association (WQA), the ion exchange softening process adds sodium at the rate of about 8 mg/liter for each grain of hardness removed per gallon of water For example, if the water has a hardness of 10 grains per gallon, it will contain about 80 mg/liter of sodium after being softened in an ion exchange water softener if all hardness minerals are removed.
Before selecting a mechanical water softener, test water for hardness and iron content. When selecting a water softener, the regeneration control system, the hardness removal capacity and the iron limitations are three important elements to consider. You may not need to soften the water, but just control the iron and manganese.
There are three common regeneration control systems. These include a time-clock control (you program the clock to regenerate on a fixed schedule); water meter control (regenerates after a fixed amount of water has passed through the softener); and hardness sensor control (sensor detects hardness of the water leaving the unit, and signals softener when regeneration is needed)
Hardness removal capacity, between regenerations, will vary with units. Softeners with small capacities must regenerate more often. Your daily softening need depends on the amount of water used daily in your household and the hardness of your water. To determine your daily hardness removal need, multiply daily household water use (measured in gallons) by the hardness of the water (measured in grains per gallon).
SummaryHard water is not a health hazard, but dealing with hard water in the home can be a nuisance. The hardness (calcium and magnesium concentration) of water can be approximated with a home-use water testing kit, or can be measured more accurately with a laboratory water test. Water hardness can be managed with packaged water softeners or with a mechanical ion exchange softening unit.