N.Y. Town Law § 209-C
The establishment or extension of an improvement district shall be based upon a map, plan and report prepared in such manner and in such detail as determined by the town board and such map, plan and report shall be filed in the office of the town clerk. In the case of a sewer, drainage or water district such maps, plans and reports shall be prepared by a competent engineer, duly licensed by the state of New York, showing the boundaries of the proposed district and a general plan of the proposed sewer, drainage or water system, as the case may be, and a report of the proposed method of operation. If a sewer or drainage district is proposed, such map shall show all outlets and the terminus and course of each proposed main sewer or drain together with the location and a general description of all sewage disposal plants, pumping stations and other public works, if any, and shall be consistent with, so far as possible, any comprehensive plan for sewers developed and maintained pursuant to section ninety-nine-f of the general municipal law. If a water district is proposed, said map and plan shall show the source of water supply and a description of the lands, streams, water or water rights to be acquired therefor, the mode of constructing the proposed water works and the location thereof, including reservoirs, water purification or treatment works, water mains, distributing pipes and hydrants, and shall be consistent with, so far as possible, any comprehensive plan for public water supply systems developed and maintained pursuant to section ninety-nine-f of the general municipal law. If, however, the supply of water to be used in said water district is to be purchased from a municipal or other corporation, or any person, then said map and plan shall set forth and show only the water mains, distributing pipes, hydrants, reservoirs, if any, and location of each. Before any sewer system is constructed in any such district, the town board shall cause a copy of the map and plan of the proposed sewer system and sewage disposal plant or proposed extension thereto to be submitted to the state department of health, and, if approved, it shall be filed in the office of the state department of health and the town clerk. The state department of health may require profiles to be submitted for any sewers or drains shown on such map and plan. Such map and plan may be amended with the approval of the state department of health and if approved, shall be filed in the office of the state department of health and the town clerk.
N.Y. Town Law § 209-C