Safety officials warn that the public is at risk of a potentially deadly release of chlorine gas, unless the government requires equipment for transportation.
The U.S. Chemical Safety and Hazard Investigation Board is urging sites where rail cars unload chlorine to install automatic shut-off valves.
About 15 million tons of chlorine are produced each year and three million tons are shipped by rail across the country.
A Safety Board survey found that 30 percent of water treatment plants lack the most effective equipment to detect and stop chlorine leaks.
Many water treatment plants that receive the chlorine are in residential communities.
For more on the CSB you can log on to its website at www.chemsafety.gov.