Among the questions we frequently receive is how one gets rid of the grungy buildup on windows, shower glass, faucets and plumbing fixtures. Our answer is to make a paste out of a bit of turpentine and some pumice powder. Or, use a strong cleaning product that contains sodium carbonate or phosphoric acid. And, of course, be prepared to use plenty of elbow grease.

Unfortunately, the repeated cleanings using powerful products can, over time, cause finishes to become dull or worn out.

Hard water is caused by excessive levels of calcium and/or magnesium in water. When water comes in contact with minerals, it creates hard water that causes buildup in water heaters, produces unsightly water stains in bathtubs and fixtures, and leaves behind soapy scum in the shower and on your skin.

The U.S. Department of the Interior classifies hardness based on the concentration of grains per gallon (gpg) of calcium and/or magnesium. To put this in perspective, a typical aspirin is equal to about five grams. If the aspirin were dissolved in a gallon of water it would add five gpg of aspirin to the water. The government classifies water as follows: less than 1.0 gpg, soft; 1.0 to 3.5 gpg, slightly hard; 3.5 to 7.0 gpg, moderately hard; 7.0 to 10.5 gpg, hard and greater than 10.5 gpg, very hard.

While hard water is not unhealthful, it can cause problems. The minerals in hard water gradually settle, forming a hard-scale surface. This scale eventually will clog pipes and diminish the efficiency of toilets, water heaters, clothes washers and automatic dishwashers. The negative effects of hard water can be reversed by use of softened water. A water softener works on the principal of "cat-ion exchange" wherein ions of the hardness minerals (calcium and magnesium) are exchanged for sodium or potassium ions. This process effectively reduces the concentration of hardness minerals to insignificant levels.

This exchange is accomplished in a tank, using a "resin" of tiny beads made from a special plastic material. The chemical composition of hardness material carries a positive ionic charge. These positively-charged ions are drawn to the negatively-charged resin material which captures the hardness material, preventing it from entering the water system.

After a period of use, the sodium or potassium ions are completely exchanged or "exhausted" and the unit must be "backwashed" or regenerated. This requires the use of sodium or potassium chloride which is loaded into a brine tank and dissolved to form a brine solution used to recharge the system.

There are three basic types of water softeners: Automatic, Demand Initiated Regeneration (DIR) and Portable Exchange. An automatic water softener is equipped with a timer that starts the regeneration process at preset intervals. The intervals generally are based on a calculation of water hardness, unit capacity and estimated water use.

In contrast to an automatic system, Demand Initiated Regeneration units use either a meter, which monitors water usage, or a sensor, that monitors a change in water hardness to regenerate when soft water runs out. Because they adjust to actual usage or change in water quality, DIR units consume up to 50 percent less sodium or potassium chloride and water than present automatic softening units.

A portable exchange unit is a type of softener with an exchangeable resin tank. When the resin material in the tank is exhausted, a fresh tank is delivered and the used tank is returned to a central plant for regeneration.

If your home suffers any of the symptoms discussed earlier, you probably have hard water. How hard is your water? While do-it-yourself test kits can be obtained at many local home centers, they are not the most reliable testing method. A more effective means of testing water quality involves collecting a sample and bringing it into your municipal water supplier or public health agency.

Many private water treatment and conditioning companies can provide water testing also. In addition to aesthetic problems such as taste, odor and hardness, the water also should be tested for health-related contaminants such as lead, nitrates, bacteria and radon - to name a few. Health-related contaminants can be treated with whole-house or point-of-use water purification systems. Water purification is for health, water softening is for aesthetics. The systems are different.

Be an educated consumer. Talk to a water treatment specialist and research which water quality improvement products you need before you buy. Check the product's capabilities, warranties, maintenance provisions and general operating instructions. Investigate which contaminants each product reduces and to what extent.

Water treatment products can vary widely in complexity and capabilities. Usually, they are sold by local water treatment dealers, as well as mass merchandisers. Look for industry seals of approval by such agencies as the Water Quality Association (WQA) and the National Sanitation Foundation (NSF).