Belmont receives its water from the Massachusetts Water Resources Authority(MWRA) MWRA treats its drinking water so that it has a pH of approximately 9.3, a slightly alkaline measurement. This pH level helps prevent water from picking up any metal particles that might be in your household plumbing.
Untreated, "raw" water in MWRA's Quabbin Reservoir has a pH of approximately 6.8, close to neutral.
pH measures the amount of hydrogen ion activity in a substance. The pH scale is relative and runs from 0 to 14. 0 is the lowest, and most acidic, pH level. 7 is neutral. 14 is the highest and most alkaline pH level.