BROAD APPEAL

Despite the disposal problems, though, desalination's appeal extends beyond California and Florida. For example:

* The Mount Pleasant Waterworks and Sewage Commission in South Carolina operates three desalting plants with a combined capacity of 6.8 mgd. On line for three years now, the facilities treat brackish water from deep wells. The well water, says Water Superintendent Melvin Bennett, has a poor taste, which is the main reason the RO plants were installed.

* On North Carolina's Outer Banks, Dare County installed an RO plant in 1989 in Kill Devil Hills to provide additional water for the summer when thousands of tourists increase the local population, putting extra demand on water resources. The facility, with a capacity of 3 mgd, taps brackish deep-well water.

* In 1993, Washington, Iowa, began operating an EDR plant to remove radium, a suspected carcinogen, from its drinking water, which originates in deep wells. Three EDR units with a combined capacity of 1.2 mgd perform that task.

* The Greater Texoma Utility Authority in Texas installed an EDR plant to acquire a new supplementary water source from a highly mineralized lake. The 4.5-mgd plant began operating in 1993.

A COMEBACK

Politically, desalination does not enjoy the favor it once did. In the 1950s and '60s, the federal government funded considerable research and development through its Office of Saline Water, and much of the advancement in RO and other technologies derived from those efforts. Support diminished in the 1970s and disappeared altogether in the '80s.

However, in recent congressional action, Sen. Paul Simon (D-Ill.) has introduced legislation providing for modest sums to "reinvigorate" U.S. desalination research. The ADA endorses the measures, according to organization Treasurer Glenn McPherson, but the current Congress is not in a spending frame of mind.

It also is in an anti-regulatory mood, and legislation such as the Clean Water Act is under scrutiny.

In the unlikely event that water quality standards are actually strengthened, desalination could be a major beneficiary, says Bill Katz of Boston-based Ionics, a membrane manufacturer. Still, he admits that population growth, and its attendant demand on water supplies, remains the real force driving desalination.

And, as technology advances, costs are lowered. For instance, one Minnesota firm recently reported development of a membrane that requires less energy for reverse osmosis. Additionally, advocates of desalination point out that it often compares favorably with the cost of developing other new sources of water like reservoirs, dams and aqueducts.

Robinson Township, Pa., got a quick - and costly - lesson in the importance of backflow prevention when a mixture of chemicals used to kill termites ended up in its water supply.

Backflow, the reversal of the flow of water and undesirable substances from any source - used water, industrial fluids, gases, etc. - can be prevented. But nearly every backflow prevention program in the country focuses primarily on commercial and industrial sites.

The Safe Drinking Water Act (SDWA), however, is making municipal water utilities increasingly aware of their responsibility to their customers. Unfortunately, budgets are shrinking, even as government regulation and operating costs increase.

Small water utilities - (Time magazine estimates that 83 percent of the nation's systems serve fewer than 3,000 customers but that, combined, they serve 20 million Americans) have been the hardest hit.

Still, small utilities are not the exception. "Meeting expected federal requirements will cost the nation's water suppliers more than $14 billion, the EPA estimates," according to a 1991 article in U.S. News & World Report. Some of that $14 billion is wrapped up in the complex array of backflow prevention devices used at commercial sites, as well as the extensive labor involved in cutting the devices into a city's water supply pipelines.

Installation is costly enough, but periodic testing requirements cause labor costs to skyrocket. Additionally, in making backflow prevention a residential issue, the SDWA has made installation and testing the responsibility of local water utilities.

Technology, however, is helping. One innovation, a residential water meter supplied to Schlumberger Water Division, Tallassee, Ala., is helping Pompano Beach, Fla., get control of its costs. The meters are fitted with backflow prevention devices within the standard 7 1/2-inch lay length. One series of meters incorporates double check regulators, and the second series integrates dual check valves within one standard meter body.

Both eliminate the need for resetters, as well as dual check and meter combinations by replacing them with an integral backflow/meter unit, making it easier for water utilities to implement aggressive backflow prevention programs economically. Both also accept encoders that serve as the basis for all the company's automatic meter reading system solutions.

Lincoln Bates is an Atlanta-based freelance writer.