President Clinton plans to announce a new regulation today requiring the nation's 5,600 water systems to notify consumers of any contaminants in their drinking water.
The proposed requirement would be modeled on one pioneered by California, but would go somewhat further than the state's rule.
Clinton is to make the announcement during a scheduled visit to the Bay Area.
"The new rule is meant to ensure that the 240 million Americans who get their drinking water from public and private water utilities are made aware, at least once a year, of any contamination and the possible health effects," said a White House spokesman.
Water companies will have to tell consumers where their water comes from, whether it meets federal drinking standards, as well as identifying any contaminants, the spokesman said. The regulation would take effect in October 1999 and does not need congressional approval.
Officials of the White House Council on Environmental Quality said the new regulation is also meant to inform consumers of the source of any contaminated drinking water, whether it comes from an aquifer, a reservoir or rivers or streams that might be vulnerable to polluted runoff.
The only people who aren't covered by the requirement are those who get their water from private wells, White House officials said.
California's current rule does not require water companies to give out information about drinking water sources. Moreover, unlike the California rule, the federally mandated notification will include information about the increased risks of various pollutants to people with immune system deficiencies and other health problems.
During the last five years, public health officials have become particularly concerned about the impact of agricultural runoff on drinking water supplies. Besides containing animal waste, the runoff is often rich in nutrients that promote the growth of bacteria.
Such runoff is believed to be the source of cryptosporidium, an organism that turned up in Milwaukee's tap water in 1993 and was blamed for an outbreak of gastrointestinal illness that victimized thousands of people and may have killed more than 100.
Agricultural runoff also is a suspect in recent outbreaks of pfisteria, a mysterious microscopic organism that is blamed for illnesses in the Chesapeake Bay region that affect learning and memory as well as causing skin rashes and breathing problems.
The new rule also represents a continuation of efforts by the administration to require disclosure of toxic releases into the nation's air and water.
"This is very much another chapter in the president's efforts to give consumers more information about the quality of air they breathe and the water they drink," said Kathleen McGinty, who heads the Council on Environmental Quality.
"The administration's philosophy is that by putting the information in the hands of the people potentially affected, you empower them to take action and that ultimately leads to a reduction in releases."