With the Senate Committee on Homeland Security and Government Affairs scheduled to hear testimony on Wednesday about proposed chemical security legislation, a new survey by the Center for American Progress identifies 554 drinking water and wastewater plants in 47 states that have replaced extremely hazardous substances with safer and more secure chemicals or processes.

More than 40 million Americans are no longer in danger of harm from a terrorist-released or accidental toxic gas plume because their water utility has converted to safer alternatives to chorine gas in water treatment.

“These facilities show what can be done with proven technologies to remove chemical hazards from communities,” said Paul Orum, who conducted the survey as a consultant to the Center for American Progress. “Unfortunately, weak federal chemical security standards don’t encourage more treatment plants to reduce their hazards.”

The Department of Homeland Security and other agencies warn that terrorists could use industrial chemicals as pre-positioned weapons. Current temporary Chemical Facility Anti-Terrorism Standards, or CFATS, exempt water utilities and do not require any facilities to look for safer and more secure chemicals and processes.

At least 2,600 additional water and wastewater facilities still use large amounts of chlorine gas.

“Leading facilities have converted, but progress is slow,” said Reece Rushing, Director of Government Reform at the Center for American Progress. “We know how to dramatically reduce the risk of toxic terrorism. But more than 2,500 water facilities still use large amounts of potentially deadly chlorine gas, threatening millions of Americans. We can do better.”

The 554 converted water facilities are located in 47 states and the District of Columbia (all states except North Dakota, New Hampshire, and New Mexico). Of the 554 converted facilities, 235 treat drinking water, 315 treat wastewater, and four treat both. Of the 315 converted wastewater facilities, approximately 140 switched to ultraviolet light and 175 switched to liquid bleach.

About two-thirds of U.S. wastewater plants already use a disinfectant other than chlorine gas, according to the U.S. Government Accountability Office. Drinking water utilities in at least 160 large U.S. cities already use liquid bleach.

Water utilities use chlorine to disinfect drinking water or wastewater. Utilities may avoid chlorine gas by switching to liquid chlorine bleach (sodium hypochlorite), which they may buy in bulk or generate on site. Wastewater plants may also avoid chlorine gas by switching to ultraviolet light. Some wastewater plants also avoid sulfur dioxide gas, used to dechlorinate, by switching to sodium bisulfite.

In November 2009, the House passed the Chemical and Water Security Act (H.R. 2868), a comprehensive chemical security standard that would include water utilities and encourage hazardous chemical plants to develop safer and more secure technologies.

“Converted facilities are safer for employees and communities while reducing potential costs and liabilities for companies,” Orum said. “Congress should ensure that high-hazard chemical facilities take reasonable steps to adopt proven alternatives.”

The 554 converted facilities together removed their toxic gas dangers to 1 million or more people in 12 states: New York, New Jersey, California, Ohio, Maryland, Pennsylvania, Florida, Indiana, Georgia, Michigan, Louisiana, and Virginia. In an additional 22 states, the converted facilities removed their dangers to more than 100,000 people.