Section 3. As used in this chapter the following words shall, unless the context otherwise requires, have the following meanings:—

''Bonds'' or ''Bond'', bonds, notes and other obligations or evidences of indebtedness of the commission issued under the provisions of this chapter.

''Commission'', the water and sewer commission of the municipality established by section three or, if said commission shall terminate as provided in section twenty, the board, body or commission succeeding to the principal functions thereof, or whatever body, person or persons to whom the powers given by this chapter to the commission shall be transferred by law.

''Costs'', applied to any extension, improvement or enlargement of the water works system or the sewer works system or to any other project of the commission financed under the provisions of this chapter; all or any part of the cost of acquisition, construction, reconstruction, alteration, and remodeling of such work, including, without limiting the generality of the foregoing, costs of labor, materials, machinery and equipment, lands, structures, and all rights of any kind in real and personal property, costs of demolitions or relocations, costs of removal or relocation of any public utilities facilities, financing charges and expenses, interest prior to, during and for a period after completion of such work, reserves for debt service and other capital and current expenses, costs of architectural, engineering, financial, legal and consulting services, costs of plans, specifications, appraisals, surveys, inspections, financial and feasibility studies, expenses of organization, administration and operations prior to the commencement of and during such work, costs of equipment and supplies and advance training of operating personnel and other expenses of completing and commencing operation of such work, working capital, and other necessary or incidental expenses to the acquisition, construction, financing and placing in operation of such work.

''Current expenses'', the commission's current expenses, whether or not annually recurring, of maintaining, repairing and operating the water works system and the sewer works system and any other properties of the commission, including, without limiting the generality of the foregoing, administrative, general system payments and other employee benefits, engineering expenses for maintenance, operation and repairs, legal, financial and auditing expenses, insurance and surety bond premiums, fees and expenses of trustees and paying agents, payments to others for services rendered to the commission, taxes which may be lawfully imposed upon the commission or its income or operations or the property under its control, and other current expenses required or permitted by law to be paid by the commission, including the funding of reasonable reserves for maintenance, repair, replacements or operations.

''Local appointing authority'', in the case of all cities, except those with a Plan D or Plan E charter, the mayor with the approval of the city council; in the case of cities with a Plan D or Plan E charter, the city manager; in the case of towns, the town meeting.

''Municipality'', a city or town which accepts the terms of this chapter.

''Revenues'', all revenues, rates, fees, charges, rents and other receipts derived from the operation of the water works system and the sewer works system and all other properties of the commission, including, without limiting the generality of the foregoing, bond proceeds, proceeds of any grant or loan to the commission, investment earnings and the proceeds of insurance, condemnation, sale or other disposition of properties.

''Sewer works system'', the existing sewer works system in the possession of and under the jurisdiction, ownership, control and regulation of the municipality, including all plants, works, instrumentalities or parts thereof, lands, easements, rights in land and water rights, rights of way, contract rights, franchises and privileges, all publicly constructed main, trunk, intercepting, connecting, lateral, outlet and other sewers, outfalls, pumping and ventilating stations, disposal and treatment plants, or works, structures, equipment, vehicles, appliances, and other adjuncts thereto, and any other property or interests in property, real or personal, incidental to and included in such sewer works system, and all facilities, betterment, extensions, improvements and enlargements thereto hereafter constructed or acquired.

''Water works system'', the existing water supply and distribution system in the possession of and under the jurisdiction, ownership, control and regulation of the municipality including, without limiting the generality of the foregoing, all plants, works, instrumentalities or parts thereof, lands, easements, rights in land, water and flowage rights, approaches, water courses, rights of way, contract rights, franchises and privileges, all connections, dams, wells, reservoirs, water mains and pipe lines, equipment, buildings, structures, vehicles, sandpipes, tanks, conduits, meters, hydrants, fire connections, fixtures, purification, filtration and treatment works and other adjuncts thereto, and any other property or interests in property, real or personal, incidental to and included in such water supply and distribution system, and all facilities, betterment, extensions, improvements and enlargements thereto and to or for the water supply therefor hereafter constructed or acquired.