According to chlorofluorocarbon dating, the water takes about 3,000 years[2] to travel underground before returning to the surface at the springs.

[3] The conduit between the mountains and the spring is the geological stratum found in parts of the northwest United States called the Madison Limestone.

Although some of the underground water from the Little Belt Mountains escapes to form Giant Springs, some stays underground and continues flowing, joining sources from losing streams in the Black Hills, Big Horn Mountains and other areas.

Giant Springs has an average discharge of 242 cubic feet (6.9 m3) of water per second or 150 million gallons per day.

[4] Today, some of the spring water is bottled annually for human consumption and some of the discharge is used for a trout hatchery.