Section 41. Towns and water supply and fire districts duly established by law may, with the consent and approval of the department of environmental protection, given after due notice and a hearing, take by eminent domain under chapter seventy-nine, or acquire by purchase or otherwise, and hold, lands, buildings, rights of way and easements within the watershed of any pond, stream, reservoir, well or other water used by them as a source of water supply, which said department may deem necessary to protect and preserve the purity of the water supply. All lands taken, purchased or otherwise acquired under this section shall be under the control of the board of water commissioners of the town or district acquiring the same, who shall manage and improve them in such manner as they shall deem for the best interest of the town or district. All damages to be paid by a town or district by reason of any act done under authority hereof may be paid out of the proceeds of the sale of any bonds authorized by law to be issued by such town or district for water supply purposes or from any surplus income of the water works available therefor. A town may also make a contract to contribute to the cost of building, by any other town situated in the watershed of its water supply, a sewer or system of sewers to aid in protecting such water supply from pollution.