Mankato council authorizes bidding for reverse-osmosis pilot at water plant

The Mankato City Council voted to authorize bidding for a reverse-osmosis (RO) pilot at the municipal water treatment plant, a step city staff said will evaluate the treatment technology's compatibility with the city's drinking-water sources and inform longer-term planning.

Councilmember Deacon asked whether the RO system would allow the city to use more water from the shallower ("rainy") wells and reduce reliance on deep Mount Simon aquifer sources. City staff answered that the pilot would determine compatibility and blending parameters; "Ultimately, we will be taking more water from the shallow wells," staff said, and the pilot will report findings to inform the final facility plan expected in October.

Staff also said an RO pilot could reduce the amount of chemicals needed in the treatment process, but emphasized that design and blending decisions will be determined during engineering.

The council approved the resolution to authorize bidding for the pilot, with members noting the pilot is an evaluation step rather than a commitment to a full-scale facility change. City staff said final operational plans, including the exact mix of source waters, will follow the pilot and subsequent facility planning.