WATER BOARD APPROVES INCREASE IN CHLORINE LEVELS

June 22, 2007

Madison-The Madison Board of Water Commissioners approved a standard operating procedure this week that would slightly raise chlorine levels at Madison wells. Board Commissioner Dr. Greg Harrington, who helped develop the policy, emphasized that the utility already meets all regulatory standards for chlorine based on public health standards. He said the change was being made to provide a margin of safety, to facilitate system operation, and to prepare for the requirements of a federal groundwater rule the utility must comply with by the end of 2009. Dr. Harrington is a professor of Civil and Environmental Engineering at UW-Madison and an authority on disinfection of water distribution systems.

The standard procedure for chlorine levels was developed by a staff team within the utility and reviewed and revised by a team made up of the utility general manager, water quality manager, principal engineer, and a system operator; the city engineer; two outside experts; and three board members, including Public Health Director Dr. Thomas Schlenker.

The current standard at the utility is to maintain a chlorine level of 0.2 mg/L leaving most wells and 0.3 mg/L at other wells in order to maintain a level of 0.1 mg/L everywhere in the distribution system. Federal and state regulations do not require the utility to chlorinate its drinking water, but requires the distribution system to be free of microbial contaminants and, if the utility does chlorinate, to maintain an annual average level of chlorine in the system below 4.0 mg/L.

The new policy approved by the board requires the utility to maintain chlorine levels leaving all wells as close as possible to 0.3 mg/L and to take action to remove a well from service if chlorine levels go below 0.15 mg/L. The goal remains to maintain levels at or above 0.1 mg/L everywhere in the distribution system. Corrective action would also be taken if chlorine levels leaving a well exceed 0.55 mg/L and a well would be shut down if levels exceed 4.0 mg/L.

Chlorine is typically added to drinking water systems to ensure that microbial organisms, such as bacteria and viruses cannot survive in the water. Utility officials said that some customers might notice an increase in the smell or taste of chlorine in the water when levels are initially raised. The chlorine levels are not a health concern and, in fact, are established to prevent health risk from bacteria and viruses.

The new chlorine levels at the wells will be phased in over the next week. If customers experience a persistent and excessive odor or taste of chlorine in their drinking water, they should call the utility at 266-4654, and it will be investigated.

Contact:
  • David Denig-Chakroff, General Manager, 608-266-4652
  • Joseph Grande, Water Quality Manager, 608-266-4654