Brentwood Water Hardness & Quality Report (2026)

The City of Brentwood Water Services supplies approximately 43,000 residents in Brentwood, Tennessee. Drinking water is sourced from the Cumberland River and treated at two filtration plants: the K.R. Harrington Water Treatment Plant and the Omohundro Water Treatment Plant. The service area encompasses Brentwood and surrounding neighborhoods including Annandale and Governor's Club in Williamson County. Both plants employ conventional filtration processes to treat river water before distribution through the municipal system to meet EPA and state drinking water standards.

Brentwood's water supply is shaped by its position atop the Nashville Basin, where water from the Cumberland River watershed percolates through layers of Ordovician limestone and dolomite formations. The geological setting — ancient limestone bedrock dissolved over millions of years — creates a very hard water supply with exceptionally high concentrations of dissolved minerals, particularly calcium carbonate and magnesium sulfate compounds leached from the carbonate bedrock. The Cumberland River watershed has also historically been affected by industrial pollution.

The very hard water in Brentwood causes significant scale buildup in water heaters, dishwashers, washing machines, and pipes, reducing efficiency and shortening equipment lifespan. A water softening system is strongly recommended to protect appliances, improve soap and detergent effectiveness, and reduce maintenance costs associated with mineral accumulation. Beyond hardness, the supply contains five contaminants detected above health guidelines, including arsenic, chromium (hexavalent), nitrate, total trihalomethanes (TTHMs), and bromodichloromethane. Potential PFAS concerns exist related to litigation involving 3M and the Tennessee River system; the utility treats water through conventional filtration at both plants to meet federal and state standards.