As House Democrats eye the expansion of its public drinking water service area, the Massachusetts Water Resources Authority (MWRA) is considering whether the communities where that water comes from should finally get to reap the benefits of the system.

The MWRA board is undertaking a preliminary study to direct water from the Quabbin Reservoir, which provides Boston and other eastern Massachusetts communities with drinking water, to the towns that surround and protect the reservoir.

The agency currently provides wholesale water and sewer services to 3.1 million people and more than 5,500 businesses in 61 communities in eastern and central Massachusetts, with the Quabbin its primary resource.

“The Quabbin Reservoir provides life for eastern Massachusetts and allows the eastern part of the state to grow and expand — and yet for far too long, far too long, the recompense for towns that steward this water has been a pittance relative to the value,” Sen. Jo Comerford of Northampton said last year.

Comerford and state Rep. Aaron Saunders of Belchertown filed a bill (S 447 / H 897) that would impose a 5 cent per 1,000 gallon excise on Quabbin water. The lawmakers estimate the tax would produce $3.5 million, which would be directed to Quabbin watershed communities and local nonprofits with a focus on these towns’ health, welfare, safety and transit.

That bill also would mandate that the MWRA explore opportunities to expand into new communities in the Quabbin watershed, as well as towns in the Westfield River, Chicopee River, Connecticut River and Millers River Valley basins. The bill is currently in a gray area as the Senate waits for the House to agree on whether to extend its reporting deadline until June.

The study the MWRA is considering would expand the water service to Ludlow, Belchertown, Ware, Hardwick, Barre, Petersham, Phillipston, New Salem, Orange, Wendell, Shutesbury and Pelham.

Some lawmakers, however, say the preliminary study is not ambitious enough.

Board members said they had met with some western Massachusetts lawmakers who think the MWRA should explore a broader scope, including some of the larger communities in western Massachusetts.

“I think the staff is viewing this as kind of the first good step,” said Colleen Rizzi, director of environmental and regulatory affairs at the MWRA. “And that’s to look at the communities right in and around the Quabbin itself, see what’s viable, what’s feasible before extending that to a larger geography.”

The expansion study is set to be completed by the end of 2024.