Boston’s Sewage System

Like many contemporary industrial cities, Boston has had sewers for hundreds of years.  These early sewers, like those located in London, were privately owned and originally designed for draining water from cellars. There were conflicts over who owned these sewers and in 1709, the Massachusetts General Court stepped in and passed an act regulating their construction, as well as fees for their use.  As these sewers were designed for water drainage, no waste was allowed into the burgeoning sewer “system.”  Eventually, a more efficient waste system was needed for the growing city, and in 1833, these old sewers were pressed into service to serve that need. Problems would quickly arise because of stagnated sanitary waste, and it was quickly thought that adding rainwater from roofs would help to “flush” the sewers.  It was ineffective, and Boston would face the same waste disposal issue facing other growing industrial cities.  Cholera, typhoid and dysentery began to increase, and over time, it determined that an inadequate sewer system was to blame.  By 1875, a study would be conducted to find a remedy to this problem, and this would lead to the construction of the Boston Main Drainage System (BMDS).[1]

The BMDS was constructed from 1877 to 1884 to collect waste from local sewers and carry it, as well as runoff rainwater, through the city to pumping stations.  The waste and rainwater would travel a portion of the 25 mile system to the pumping stations, eventually reaching an offshore disposal point.  As Boston continued to grow, the sewer projects were expanded in size and scope. However, there were still areas of the city that were outside the service area. To address this need, the Metropolitan Sewerage System was formed in 1889, becoming the first modern sewer system of its kind.[2]  Although Metropolitan Boston’s sewer system was considered “one of the best in the country 100 years ago,” years of poor planning and neglect would nearly ruin it.  Wastewater, still “merely collected and deposited into Boston Harbor,” would pollute the area, causing ruinous damage to the clam and shellfish industries.

Eventually, it was decided to “treat” the waste before sending it out to sea with the high tide.[3] Offshore treatment facilities were built, further expanding the system.    A new outfall tunnel moves waste out of the harbor to a more distant and deeper water location in the Massachusetts Bay.  Diffuser heads now allow for 100 parts seawater to 1 part waste ratio, which serves the immediate needs of the Boston area.  These strategies have solved many of the centuries old questions of adequate waste removal, however for as advanced as they have become, sanitary waste still is still put in the water and sent out with the tide.[4]



Diffuser Cap:

Initial dilution of the effluent from the new diffusers is about 1 part treated effluent to 100 parts seawater.


Boston Water and Sewer Commission.  (13 January 2010).

Massachusetts Water Resources Authority. http:/ /  (13 January 2010).

Massachusetts Water Resources Authority. (13 January 2010).

[1] Boston Water and Sewer Commission.  (13 January 2010).

[2] Massachusetts Water Resources Authority. (13 January 2010).

[3] Ibid.

[4] Boston Water and Sewer Commission.

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