The Biscayne Aquifer, an underground geologic formation, is the source of raw water for the Miami-Dade County Water and Sewer Department (WASD). Approximately 330 million gallons per day (mgd) are withdrawn from the aquifer through wells extending an average of 80 feet below the ground surface to meet the needs of the community.

As water travels over the surface of the land or through the ground, it dissolves naturally occurring minerals and can pick up substances resulting from the presence of animals or from human activity. In order to ensure that tap water is safe to drink, EPA regulates the contaminants in water provided by public water systems.

Water suppliers use a variety of treatment processes to remove contaminants from drinking water. These individual processes may be arranged in a "treatment train" to remove undesirable contaminants from the water. The most commonly used processes include filtration, flocculation and sedimentation, and disinfection. Some treatment trains also include ion exchange and adsorption. A typical water treatment plant would have only the combination of processes needed to treat the contaminants in the source water used by the facility. If you want to know what types of treatment are used for your water supply, contact your local water supplier or public works department.

Miami-Dade County water is pumped to WASD’s water treatment facilities and in some areas to municipal water treatment facilities: Hialeah, John E. Preston, Alexander Orr and the South Dade Water Supply System. 

The Hialeah and Preston Plants serve residents who live north of Flagler Street up to the Miami-Dade/Broward Line. The Alexander Orr Plant serves residents south of Flagler Street to S.W. 248 Street.

Highly trained microbiologists, chemists and water treatment specialists conduct or supervise more than 100,000 analyses of water samples each year. Water quality samples are collected throughout the county and tested regularly. Samples include untreated and treated water taken at our facilities, sample sites throughout the service areas and at customers’ homes. These tests are overseen by various regulatory agencies on a federal, state and local level. From these three regional water plants supply treated water to a common distribution system.

The South Dade Water Supply System is comprised of five smaller water treatment plants that serve residents south of S.W. 248 Street in the unincorporated areas of the County. These five plants pump treated water into a common distribution system, which is separate from the main system.

Customers judge the quality of their drinking water based on taste and appearance. The water delivered to residents in the northern part of the county originates from a region of the Biscayne Aquifer that contains natural organic material. These natural substances increase the color of the water. Although the water has a yellow tint, there is no harm associated with the color.