Greater Sudbury Water and Wastewater Services has picked up a trick or two from the mining industry, substituting hard-rock tunnels for traditional trunk sewers along 13 miles of its system. Unique in the world, the system has proved to be both cost-effective and durable, requiring little to no maintenance over more than a half-century.

Greater Sudbury, Ontario, is located about 250 miles north of Toronto. The area has become famous for its mining operations, harvesting...