CSST proponents cite an endorsement by Factory Mutual Research of CSST as "a viable and preferred alternative to rigid black iron piping, particularly in locations subject to considerable seismic activity." They noted the U.S. Geological Survey counted nearly 500 earthquakes (most too small to be felt) in California during a recent one-week period.

"The risk of earthquakes in California is one we have all come to live with, but one in which everyone desires, and deserves, the best protections," said Stephen Gadomski, professor and chair of the Department of Civil Engineering and Applied Mechanics at California State University, Northridge, in written testimony provided to HCD. "The advantages of flexible piping, in that it can be bent to more than 360 degrees and better withstand impacts from tipping appliances, make it a very attractive option for protecting lives and property in those parts of the state that are prone to earthquakes."

Manufacturers also pointed to guidelines developed by the California Seismic Safety Commission stating, "Flexible pipes for gas and water lines are safer in an earthquake than rigid pipe." Opposition to CSST was spearheaded mainly by pipe trades unions.

HCD had scheduled a public hearing and was accepting written comments through November before making a final recommendation.