The Massachusetts Water Resources Authority (MWRA) is a public authority in the Commonwealth of Massachusetts that provides wholesale drinking water and sewage services to 3.1 million people in sixty-one municipalities and more than 5,500 large industrial users in the eastern and central parts of the state, primarily in the Boston area.

The Quabbin Reservoir is the largest inland body of water in Massachusetts, and was built between 1930 and 1939. Along with the Wachusett Reservoir, it is the primary water supply for Boston, 65 miles (105 km) to the east, and 40 other cities and towns in Greater Boston. The Quabbin also supplies water to three towns west of the reservoir and acts as backup supply for three others. By 1989, it supplied water for 2.5 million people, about 40% of the state's population at the time. It has an aggregate capacity of 412 billion US gallons (1,560 GL) and an area of 38.6 square miles (99.9 km2).