For more than two years, Donny Beasley of Tri-State Water in Cape Girardeau, MO, has been including a free bag of potassium chloride with every water softener he's sold. "We don't sell price. We sell value-added softener/RO packages . . . Potassium chloride fits our marketing strategy because it offers added health and environmental benefits over salt. Eighty-five percent of our new softener customers continue to use potassium chloride, purchased from us," adds Beasley. Today, Tri-State sells and delivers only potassium chloride as a softening agent.

Water softening by ion exchange is a mature industry. For more than 60 years, this technology has brought "the soft life" to millions of North American families. For all but the last 10 of those years, sodium chloride (NaCl), or regular salt, has exclusively been used as the regenerant in water softeners. However, there has been a slow but steady growth in the use of potassium chloride (KCl), which is chemically related to salt and has the same water-softening characteristics. It is also widely used throughout the agricultural industry.

Potassium is an essential plant nutrient which helps regulate the overall quality and health of crops. Potassium chloride is a naturally occurring mineral, often found near large deposits of salt. Virtually all KCl mined in North America comes from Saskatchewan, Canada, where processing facilities produce more than 10 million tons per year, most of which is marketed as agricultural plant food.

Most water softeners remove hardness (calcium and magnesium) and iron from water through an ion-exchange process. With salt pellets in the softener, hardness and iron are held in the resin and sodium is released to the softened water. The harder the water, the more sodium is added to effect softening. Also, native sodium may be naturally present, increasing the total amount of salt found in softened water.

Using potassium chloride pellets will not release any additional sodium into the water during the ion-exchange process, and native sodium may actually be reduced. No adjustments to the softening equipment are necessary. However, in areas where native sodium is a problem, the capacity of the water softener should be increased to take into account the removal of hardness, iron and native sodium.

Changing Regenerants

If you are converting from salt to KCl, you may blend both in the same brine tank without consequence. Most household softeners operate at an efficiency level (hardness capacity divided by pounds of regenerant) of 2,500 to 3,500 grains per pound of regenerant.

For the vast majority of water softeners currently used or marketed, no additional potassium chloride is required. There are some high-efficiency units, requiring 4 pounds of salt per cubic foot of resin, that will require up to 12 percent more KCl.

For example, normal household water softeners would require no equipment changes or adjustments at the 6- to 15-pound setting. At the 4-pound setting, however, you would adjust to 4.5 pounds to compensate for increased KCl use.

According to medical studies, the human body needs both salt and potassium for good health and avoidance of high blood pressure and other serious conditions. The key is balance.

Based on a recommended daily intake of two liters of water, a person would ingest approximately 252 milligrams (mg), or 126 milligrams per liter (mg/l), of sodium in water that was originally 16 grains hard and softened with NaCl as the regenerant. That represents nearly 13 percent of the recommended daily adult sodium dietary level of 2,000 mg. U.S. drinking water standards require less than 20 mg of sodium per liter for people on restricted diets, which represents 10 percent of the population.

In contrast, the same water, softened by KCl would add no sodium to a person's daily diet, and the individual would receive a dietary bonus of potassium in the amount of 427 mg, or 22 percent of the minimum recommended daily requirement of 1,950 mg of adult dietary potassium. Other dietary sources of potassium include bananas, oranges, lettuce, beans, peas and fresh vegetables. A study from the University of Mississippi states that consuming foods rich in potassium helps keep blood vessels healthy through protection against hardening of the arteries.

KCl and the Environment

Because potassium is a primary plant nutrient, its potential for softening water is beneficial when looking at disposal options for waste brine.

One good example is where the sewage sludge or effluent from a facility are being used for fertilization and/or irrigation of agricultural land. Both sewage sludge and effluent are deficient in potassium. Where sewage effluent is being used for irrigation of crops or lawns, excessive sodium buildup in the soil is of concern to farmers and environmentalists.

Today, softeners are being targeted as one of the major sources of sodium and chlorides to the effluent. Using KCl as a regenerant reduces the amount of sodium present in the effluent, replacing it with potassium. KCl is less damaging to the soils and less mobile than sodium, especially in high-clay soils. Potassium is absorbed by plants and reduces the potential for migration into ground water.

The use of potassium chloride as a regenerant will also result in a reduction of 12 to 20 percent in total chlorides being discharged to septic or sewage systems.

Last year, North American potassium chloride sales to the water softening industry amounted to less than 1 percent of an estimated 3.6 million tons in salt sales (which were up from 3.3 million tons in 1993). NaCl is still clearly this industry's regenerant of choice, but there are signs marking increased use of KCl.

Governmental and environmental concerns over brine solution disposal have spread nationwide. The City of Santa Barbara, CA recently recommended in writing KCl to water softener owners. Dealers who sell potassium chloride pellets report that the environmental benefits are becoming more important to consumers, although the sodium-free aspect continues to be of primary importance.

Dealer-approved

Bill Clark of CBS Systems, an independent water treatment dealer in San Antonio, TX, has been selling KCl since 1989. "We first took it on as a defensive marketing tool," says Clark. "People were telling us they would buy a softener if it weren't for the sodium/health issue, an objection, of course, that we had been trying mightily to overcome by defending NaCl.

Clark said that CBS originally sold potassium chloride as an option alongside the salt products his business always offered. Soon he dropped salt in favor of selling only KCl, to portray a "responsible image" to his customers. He added that 99 percent of their new softener customers continue to buy delivered potassium chloride, even though CBS's delivered price is nearly twice that of salt sold at large retail supermarkets and home centers.

Like Tri-State's Beasley, Clark claims most customers choose to buy dealer-delivered KCl out of a growing sense of environmental awareness. However, he agrees with Beasley that the primary motivation for most KCl customers is the sodium-free health advantage for their families.

The potential for potassium chloride's continued market growth as a water softening regenerant looks promising as more and more customers take advantage of its health and environmental benefits.

Constance Stewart is head of product sales for K-Life water softener crystals, a product of Kalium Chemicals, Rolling Meadows, IL, a subsidiary of The Vigoro Corp.