The watershed area is about 23.6 square miles, and lies within portions of the four communities. Water collected in the Hobbs Brook reservoir flows to Stony Brook Reservoir. From Stony Brook, water flows into and underground pipeline through Waltham and Watertown to Fresh Pond in Cambridge. At Fresh Pond, the water is treated and pumped to the Payson Park reservoir in Belmont where it flows by gravity into the distribution system. Alum is added to the water to remove color and organics.
Conventional filtration is done to sift out any other organics, sand, silt, and microorganisms.
All of these chemical additions are pursuant to the federal and state guidelines. People who have diagnosed cases of hypertension are usually on a salt restricted diet. People concerned about sodium intake should consult their doctor. 9 Saltine Cracker one 21 Cambridge Water 12 oz. Diet Coke 12 oz.