Seating’s limited at a Des Moines forum for the public tonight on disaster preparedness. Officials at the University of Iowa College of Public Health and state emergency-management division will tell how events since September eleventh have changed the view of security. Des Moines waterworks chief L-D McMullen, one member of the panel, says northeastern Iowa’s blessed with clean water in underground supplies that would be hard to contaminate, and in the southwest, surface water has required towns to build efficient treatment plants.Either way he says we’ve got good groundwater or good treatment systems. McMullen’s been a popular speaker at water-treatment plants since the floods of 1993 created an emergency for Des Moines, and he says there are three concerns for caretakers of drinking-water supplies.The structures, which could be physically damaged, so the utility can’t clean up the water. Second worry would be source water, like a river, being contaminated with something that couldn’t be easily cleaned up. Water utilities, like any other, rely heavily on computers and if the computers were disrupted it could be hard to operate the equipment. The program planned with the Iowa Hospital Association is the first in a statewide College of Public Health educational outreach series.