Harmless Sodium Permanganate Residual May Turn Tap Water Pink

Bloomington, Ind. – City of Bloomington Utilities (CBU) experienced an equipment malfunction at the Monroe Water Treatment Plant that may result in some customers noticing a pink tint to their tap water in the coming days. The pink tint does not pose any threat to human health. The Indiana Department of Environmental Management has been notified of the incident, and CBU has taken the necessary measures to ensure the safety of Bloomington’s drinking water. 

When the water plant experiences a period of low demand, treatment operators will often utilize that time to shut off portions of the plant to conserve energy or for routine maintenance. In this instance, the pump controlling the feed of a treatment chemical called Sodium Permanganate malfunctioned resulting in overfeeding. The problem was discovered by the treatment operators and rectified. 

Sodium Permanganate is an oxidant used to control taste and odors, control biological growth in treatment plants, and remove iron and manganese. It can help to reduce the formation of disinfection byproducts (DBPs) by oxidizing precursors and reducing the demand for other disinfectants, such as chlorine. Monroe operators have increased the feed rate for powdered activated carbon (PAC). U.S. EPA recommends PAC to mitigate the aesthetic effects of Sodium Permanganate.

Although a Permanganate residual may give water a pink color, it does not affect taste and poses no risk to human health or plumbing systems. 

CBU anticipates that it will take several days for the affected water to move through the distribution system, generally from south-to-north. At any specific address, pink discoloration should not persist for a period of more than several hours to one day. If water appears tinted, it is recommended that customers postpone washing clothes until the water clears. If customers have questions or concerns, or if their water has a very noticeable color change, please contact the City of Bloomington Utilities at 812-339-1444.