Lima Water Hardness & Quality Report (2026)

Lima City Water Treatment Plant serves over 65,000 residents in Allen County, Ohio, primarily the city of Lima and surrounding areas. The utility draws raw water from five above-ground reservoirs: Bresler Lake (4.9 billion gallons) and Williams Reservoir (5.4 billion gallons) on the west side, filled from the Auglaize River; and the east-side complex of Ferguson, Metzger Lake, and Lost Creek Reservoirs (4.0 billion gallons total) sourced from the Ottawa River. The plant treats this surface water to meet EPA standards before distribution.

The reservoirs are part of the Auglaize and Ottawa River watersheds within the broader Maumee River basin, traversing limestone-dominated terrain of northwest Ohio. Silurian and Ordovician bedrock formations — including dolomite and calcium carbonate-rich layers — underlie the region, influencing water chemistry through mineral leaching. This geology results in a moderately hard supply, with natural dissolution of limestone creating elevated mineral content that persists through reservoir storage and treatment.

At moderately hard levels, water causes noticeable scale buildup in pipes, fixtures, and appliances, reducing efficiency and lifespan. Hot water heaters, dishwashers, washing machines, and coffee makers are most affected, leading to higher energy bills and frequent maintenance; scale can clog aerators and reduce water flow. Regular vinegar descaling helps, but a water softener is recommended to prevent damage, improve soap lathering, and protect plumbing. Lima City earns an F water quality grade from TapWaterData, with 3 contaminants exceeding EPA health guidelines and 1 MCL violation recorded; PFAS chemicals, chromium-6, and disinfection byproducts are notable concerns despite meeting legal limits; treatment involves conventional surface water processes.