Water Softeners

A water softener is popularly defined as any substance or device that is able to eliminate, or in some way inactivate, hard- water minerals that are commonly found in water supplies. It should be noted that hard water is usually defined as having a dissolved calcium and magnesium concentration at or above 120 mg per liter. However, many people find that a concentration of only 85 mg per liter still creates some of the problems associated with hard water.

What are some typical hard-water problems? One is the crusty white buildup that can occur on the interior of your plumbing fixtures and water pipes. This lime scale is actually formed by the minerals precipitating (coming out of solution). Another problem is that calcium and magnesium minerals in water can react with the fats and oils in the soaps you use, creating an insoluble scum known as soap curd. In addition, white fabrics washed in hard water can acquire a grayish tinge.

Although most people use the term “water softener” to mean anything that can counter the effects of hard water, you should be aware that there’s a technical distinction between the terms water softener and water conditioner. Water softeners are devices that add a substance to the water to eliminate or inactivate hard-water minerals, while water conditioners are devices that don’t add anything to the water. On the other hand, water-softening agents are simply substances (not devices) that one can add to water to deactivate or eliminate hard-water minerals. (Note: Some water-softening devices help remove or inactivate iron and certain other minerals besides just calcium and magnesium.)

Water-Softening Agents

Certain compounds, when added to hard water, act as water-softening agents. What they actually do is combine with the dissolved minerals, causing them to precipitate (be pulled out of solution), thus creating very minute insoluble solids. This process, known as water softening through precipitation, causes the hard-water minerals to be chemically bound up so that they’re no longer free to react with soap to form scum (soap curd), or to attach themselves to the interiors of pipes, etc. and form lime scale.

Today, borax and sodium carbonate are two commonly used water-softening agents. For many years phosphate compounds were very popular for this, including trisodium phosphate (TSP) and sodium hexametaphosphate. However, because it was determined that phosphates can create water-quality problems in streams and other waterways, their use has declined dramatically. In homes, water-softening agents are generally point-of-use products. In other words, they’re not typically added to the entire water supply of the house, but usually just to your laundry’s wash water.

Typical Water-Softening Devices

Water-softening devices were created to provide continuous whole-house water softening. They work through a...