CORPUS CHRISTI, Texas (AP) — A South Texas city dealing with a boil water order for nearly a week plans to change disinfectant in the system in hopes of soon lifting the advisory.

Corpus Christi officials on Wednesday planned to ask the Texas Commission on Environmental Quality to allow switching to a more aggressive type of disinfectant.

City Manager Ron Olson resigned Tuesday amid the lingering supply problems that led to a boil water order issued last Friday night. Experts cited low chlorine disinfectant levels in the water supply for city of more than 300,000.

The order requires water for drinking, cooking and making ice to be boiled.

Heavy rain and street flooding this week in Corpus Christi added to the problems by complicating the water sampling process.

Officials say no E.coli has been detected.