A prospective class action lawsuit has been filed on behalf of three Glastonbury residents who allege the Metropolitan District Commission unlawfully charged them a surcharge totaling more than $1,000 each over a nine-year period.

The lawsuit—filed Tuesday in Hartford Superior Court—comes four days after the Connecticut Supreme Court upheld a lower court ruling finding the charges from 2006-2014 were not lawful.

The lawsuit claims the MDC wrongfully charged water customers in East Granby, Farmington, Glastonbury and South Windsor a nonmember town water surcharge. The MDC supplies water and sewer services to the eight member towns. The four nonmember towns are provided water service, but not sewer service.

Craig Raabe, attorney for plaintiffs William and Laurie Paetzold, and Andrew Pinkowski, said Wednesday that about 9,000 businesses, residents and town facilities could be part of the class.

“Not everyone in those towns are part of the class action, only those who have city water,” said Raabe, a partner with Izard, Kindall & Raabe in West Hartford. While the total suit could be worth several million of dollars, Raabe said he will not know the amount until discovery.

In her May 2016 ruling, Hartford Superior Court Judge Susan Peck said the surcharges were illegal, and anyone who paid them is entitled to damages.

“There is no question that if the surcharges are unlawful, then the plaintiff can demonstrate damages for the years the surcharges were imposed,” Peck wrote.

The annual surcharges for the plaintiffs varied during the nine years in question and went from a low of $41.40 in 2006 to a high of $423 in 2013. The surcharge was $158.10 in 2012 and $198.96 in 2014. It's not clear why there was a spike in 2013.

Neither MDC counsel R. Bartley Halloran or MDC Chief Executive Officer Scott Jellison could be reached for comment Wednesday.

In October 2014, a state law took effect governing the surcharges going forward. That law states that charges to nonmember communities must be consistent with member communities. Member communities during the nine-year period in question did not have a surcharge fee.

The lawsuit cites three counts: breach of contract, breach of good faith and fair dealing, and unjust enrichment.

Assisting Raabe in the case are colleagues Robert Izard and Mark Kindall.