The government's failure to regulate adequately the bottled water industry means consumers may be paying more for water that is less safe than tap water, congressional investigators and lawmakers said Wednesday.

The General Accounting Office issued a report that said bottled waters may contain potentially harmful levels of contaminants.The Food and Drug Administration "can do more to ensure the safety of bottled water," the report said.

The watchdog agency prepared the report at the request of Rep. John Dingell, D-Mich., chairman of the House Energy and Commerce Committee. The panel's subcommittee on oversight and investigations held a hearing Wednesday, culminating a yearlong investigation.

"Numerous authorities . . . have expressed concern regarding the amount and effect of microbiological contaminants found in bottled water which is stored indefinitely at room temperature," Dingell said.

"Moreover . . . the consumer is subject to confusion or worse arising from the lack of regulation and overly aggressive marketers," he said.

Fred Shank, an FDA official scheduled to testify later in the hearing, said in advance that the agency "has no reason to question the safety of bottled water."

He defended the agency's record on responsiveness, and said the FDA records indicate "bottled water has a low potential for contamination or for causing sickness."