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.

[2] The authority receives water from the Quabbin and Wachusett Reservoirs and the Ware River in central and western Massachusetts.

For sewage, it operates a large treatment center on Deer Island at the mouth of Boston Harbor, among other properties.

Near Route 128 and the Charles River, it splits in two, feeding regional distribution lines at the Loring Road Tanks[15] and an interconnection with the City Tunnel passing into Newton.

The seven zones, measured from "Boston City Base" level are approximately:[9] The major MWRA water storage facilities outside of the source reservoirs are listed below.

Covered storage facilities (242.7 million US gallons (919,000 m3) total capacity) are in primary use, and surface reservoirs are used as backup only.

Before the Hultman and Cosgrove aqueducts were built this served as the primary method of transmission for water from the Wachusett Reservoir.

One wind turbine is located at the Charlestown sewage pumping station, near Encore Boston Harbor, with a rated capacity of 1.5 MW.

[29] As a large customer, the MWRA also generates its own electricity at Deer Island Sewage Treatment Plant and Carroll Water Treatment Plant during periods of high demand to earn money with demand response contracts and to avoid high peak-time prices.

Jamaica Pond was used as a water source for Boston starting in 1795, using wooden pipes (later with cast iron).

Some distribution mains serving the Boston Low Service area date to the period when water was gravity-fed from the Brookline and Chestnut Hill Reservoirs.

[19] Population growth and the increasing popularity of indoor plumbing continued to put pressure on the region's water supply.

The Dorchester Tunnel allowed the relegation of the Sudbury Aqueduct and Chestnut Hill Reservoir to backup status, which also improved water quality.

Demand for water exceeded the "safe supply" of 300 million US gallons (1,100,000 m3) per day (for which precipitation is reliably available) starting in 1969.

These are now the primary local storage; the remaining small uncovered reservoirs are only used for backup because the water from these basins would require further treatment.

The MetroWest Water Supply Tunnel was finished in 2003, allowing rehabilitation of the increasingly leaky Hultman Aqueduct.

Given that conservation efforts brought demand well below the MWRA-defined "safe yield", and desiring to amortize over more ratepayers the fixed costs of large projects like the MetroWest Tunnel and Deer Island sewage treatment plant, the MWRA is seeking to add more wholesale water customers, including municipalities and properties straddling the border of its service area.

At the same time, certain communities in Massachusetts are facing a shortage of available water due to population growth or other factors.

[39] In 2016, during the Flint water crisis, the MWRA board approved $100 million in zero-interest loans for lead pipe removal.

Each affected municipality is responsible for designing and operating its own program; MWRA estimates this funding will be enough to removal all lead service pipes from the entire system.

[39] Burlington, Massachusetts town meeting voted in 2018 to connect to the MWRA via Arlington, to make up for a partial shutdown of its Vine Brook Treatment Plant due to wells contaminated with 1,4 dioxane.

It started the process of making an emergency interconnection to the Lynnfield Water District, which is supplied by the MWRA.

[46] MWRA also has a program to finance replacement or lining of local water mains, to maintain quality for consumers.

[47] In 1884, the Boston Main Drainage System was completed, carrying sewage from 18 towns to Moon Island to be held for an outgoing tide.

[49] Federally mandated projects to reduce combined sewer outflow events into Boston Harbor and local rivers were ongoing as of 2004.

[54] The system also has a number of combined sewage overflow prevention storage tunnels and emergency discharge points.

[53] The source towns and college pay the city of Worcester for treatment and MWRA for operational costs based on flow rates.

Through annual comments and recommendations on the Authority’s proposed capital and current expense budgets and rates, the Advisory Board provides a ratepayer perspective on the MWRA’s plans and policies to improve the region’s water and sewer systems."

"The water and sewer rates cited on the following pages for average annual household use are based on the industry standard of 120 hundred cubic feet (HCF), or approximately 90,000 US gallons (340,000 L).

With the sewer treatment facilities on Deer Island complete, the clean-up of Boston Harbor has gained national acclaim as one of the greatest environmental success stories of our time.