CARY - The Cary/Apex Water Treatment Plant will temporarily stop adding ammonia to its water treatment disinfection process beginning Thursday.

Customers who use kidney dialysis machines should be aware that their tap water may contain chlorine, ammonia or a mixture of the two at the beginning and end of March.

This monthlong annual process is required of municipal water systems and is being conducted in conjunction with other area municipalities. The water plant will resume adding ammonia to the water treatment process on April 1.

The Cary/Apex plant provides treated water to Cary, Apex, Morrisville, the Raleigh-Durham International Airport and the Wake County portion of Research Triangle Park.

The state requires all water systems that add ammonia to cleanse their systems annually by switching to free chlorine and flushing the system.

Customers are encouraged to check their water before washing white clothes. If the water appears discolored, customers should try flushing all house faucets for a few minutes.

Residents who have questions or whose water fails to run clear should call the Cary Public Works and Utilities Department at 469-4090. More information: Annual Water Disinfection at www.townofcary.org/depts/pwhome.htm.