Louisiana's health department says it has issued an emergency rule requiring that water systems in the state maintain a higher disinfectant level.
The rule announced Wednesday also will require systems to increase their water sampling sites by 25 percent.
The department says most drinking water systems in Louisiana will be required to meet the higher standard by February.
The new rule follows the discovery in recent months of a deadly amoeba in two Louisiana water systems.
The amoeba was found in water treated by St. Bernard Parish, where a boy was infected in August, and a DeSoto Parish district where a woman died in 2011.
The health department says it is also convening a group of experts to discuss the amoeba known as Naegleria fowleri.