Annapolis Water Hardness & Quality Report (2026)

The City of Annapolis Department of Public Works operates the water utility, sourcing all supply from eight groundwater wells drilled 250 to 1,000 feet deep into the Magothy, Upper Patapsco, and Lower Patapsco aquifers. Water is treated at the City of Annapolis water treatment facility before distribution through a comprehensive network serving residents and businesses in Annapolis, Maryland, within Anne Arundel County. The plant produces over 1.5 billion gallons annually to meet demand. Annapolis relies entirely on these confined coastal plain aquifers, with no surface water sources involved in the supply.

The Magothy, Upper Patapsco, and Lower Patapsco aquifers are Cretaceous-age formations within the Atlantic Coastal Plain province of Maryland, consisting of unconsolidated to semi-consolidated sands, gravels, and clays deposited during the retreat of ancient seas. The Patapsco aquifers belong to the Patapsco Formation, while the Magothy is a younger overlying unit. Both are known for moderate mineralization through prolonged contact with calcium and magnesium-bearing sedimentary minerals, contributing to a moderately hard character without extreme dissolution.

Moderately hard water promotes moderate scale buildup in appliances such as water heaters, dishwashers, and coffee makers, reducing efficiency over time; pipes and fixtures may show visible mineral deposits. Regular maintenance involves periodic vinegar descaling, installing drain screens, and flushing heaters yearly. A water softener is recommended for households with aesthetic concerns or high-use appliances. Third-party testing notes exceedances of health guidelines for bromodichloromethane, a disinfection byproduct; official reports confirm compliance with federal standards. Treatment includes aeration, filtration, and chlorination at the plant; the Anne Arundel County 2024 CCR affirms overall safety.