HARD OR soft? When it comes to water, scientists are still debating.

Studies in 1977 with a large number of people seemed to indicate that hard water is better for you. The minerals in hard water were believed to help prevent cardiovascular disease, according to Dr. Robert J. Gordon of the National Academy of Sciences. But, he said, a current study with a smaller sample seem to show that hard water has little effect on heart disease.

"Economically speaking, soft water is practical because it lathers faster -- less soap is needed to get up a good lather," Gordon said, "And consumers are concerned about getting more for their dollar than they are worried about the possible heath hazzards of soft water."

"It's a tricky question," admits Gordon in regard to the health hazzards. "We really haven't been able to pin it down." $ dr. David Schnare, senior environmental scientist for the Office of Drinking Water at EPA (Environmental Protection Agency), agrees. "Nobody really quite knows."

The hardness of water is measured by the amount of calcium carbonate present in the water. Calcium carbonate is a major component of limestone. The carbonation visible when you shake a test tube of hard water is the result of various minerals in the water such as calcium, magnesium and iron.

The hardness of water varies across the country, says Schnare. Soap manufacturers tailor their product to the area. In Iowa, Schnear says, where the water is very hard, soap with extra phosphates is sold. Phosphates -- a water softening agent -- makes water easier to lather. However, in New Hampshire, where the water is very soft, the soap you find on the market is made without phosphate.

Some jurisdictions have banned phosphates as pollutants. Phosphates contain the chemical phosphorus, which can cause algae growth. Algae uses the oxygen in water, needed by fish. Algae can also produce thick vegetation that makes boating and swimming impossible.

The water in the Washington area is labeled "moderately hard." Hardness in water is measured by parts per million (so many parts of calcium carbonate to 1 million parts of water); or by grains per gallon (so many grains of calcium carbonate to 1 gallon of water). One grain per gallon equals 17.1 parts per million. According to EPA's Schnare, a measurement of 75 parts per million is soft water; 150 and up is hard. "Water in this area tends to register at about 115 -- not very hard," says Schnare.

"This isn't surprising," says Schnare, "since most of our water comes from rivers. River or "surface" water tends to be soft, while ground water contains more minerals and so is usually hard."

Well and canal water is hard and often require water softening systems. Rainwater tends to be soft, so when rainfall is heavy, water is soft. During droughts, water is harder.

The Washington area is serviced by three water sources: The Fairfax Water Authority, which gets its water from the Occoquan River and serves 70 percent of Fairfax, all of Alexandria and the eastern part of Prince William County; the Washington Suburban Sanitary Commission (WSSC), which gets its water from both the Patuxent and Potomac rivers an serves Prince Georges and Montgomery Counties; and the Washington Aqueduct, operated by the Army Corp of Engineers. The Aqueduct's water source is the Potomac and its supply serves the Distict of Columbia.

James Warfield, public information spokesperson for the Fairfax Water Authority, says it measures hardness in water according to the U.S. Geological Survey: 0 to 60 parts per million is soft; 61 to 120 is moderately hard; 121 to 180 is hard; and anything over 180 is very hard. "We average between 65 and 75 parts per million.

Beverly Warfield (no relation to James Warfield), a chemist at WSSC's Potomac plant, says its water as of May 1981 measures 5.6 grains per gallon or about 95 parts per million -- again moderately hard. "In 1980, the average tap analysis showed 7.2 grains to 123 parts per million -- slightly harder than usual because of the low rainfall last year," explains Warfield.

Harry C. Ways, chief of the analysis division at Washington Aqueduct, says that its water is also moderately hard -- about 100 to 125 parts per million. The Potomac River is harder than the Occoquan or Patuxent, says Ways. However, it's not hard enough to use a water softening system. "There is no economic justification for softening water in this area," says Ways. "We [at the Aqueduct] don't treat the water and do not see the need for the homeowner to do so." Chemist Brad Fisher of WSSC adds, "besides ridding hard water of undesirable minerals, water softeners also rid hard water of minerals that are good for us."

Water softner manufacturers and dealers, understandably, still recommend their products for the Washington area. Next week HELP looks at water softening systems.