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Water & Sewer Systems

Boston was incorporated as a town in 1630 and later as a city in 1822. Boston is home to New Englandís oldest and largest water and sewer systems and it is one of the oldest in the country. As Boston became a more popular place to live, the town (and later the city) needed to identify and establish a safe, reliable and healthy water and sewer system. Four major factors have promoted the development of the water and sewer systems to its present day capacity and configuration.

sewer map of Boston
Main Drainage Map

First, the expansion of the city limits. Boston grew from a peninsula of 1.2 square miles to its present size of 47.8 square miles through annexation and land reclamation. Second, Boston experienced a steady increase in population and economic growth. When the first public water supply was introduced in 1848, the city had a population of about 127,000 and in 1877, the original sewer system was built in response to growing public health concerns. Presently, the population of Boston is around 590,000. Thirdly, because of this growing population, water consumption continued to increase, forcing city planners to identify new sources of water in the western section of the state. And finally, provisions for a fire protection system were sorely needed. The downtown business district of early Boston was constructed of wooded framed dwellings and businesses and particularly vulnerable to fires.

Chelsea Creek Steel Cylinder 1900

The water and sewer systems have a long and interesting history and development, and they are a tribute to the resourcefulness and commitment of many people. Today, these systems are run by the Boston Water and Sewer Commission (BWSC), which was created to maintain and improve the quality and reliability of water and sewer services in Boston.

The following pages are separated into two sections: Water System and Sewer System. Within these sections, you will find a description of the present-day water and sewer systems, the histories of the water and sewer systems, and how water is distributed and consumed. Within the sewer section you will learn how wastewater is collected, treated and discharged. And finally, there are sections on combined sewer overflows (CSOís) as well as the stormwater system. These sections provide an overall picture of Bostonís past and present water and sewer systems.