Convincing homeowners to put their own money behind a private-side inflow-and-infiltration project seems impossible, but one Minnesota utility found a formula that resulted in over 10,000 foundation drain disconnections.

Overall, Duluth has eliminated around 26 million gallons a day of I&I from its system during rain events through private-property I&I reductions and utility projects. Using public education and cost sharing, as well as implementing potential penalties for...