N.Y. Envtl. Conserv. Law § 15-1521
On any application for a new or increased withdrawal of water for a public water supply system, the department may require or authorize the applicant to make provisions for the supply and to supply water to any area of the state which as determined by the department in its decision on that application properly should be supplied with water from the source or sources of water supply sought by the applicant. The owner or operator of any existing or proposed public water supply system within such area may apply to the department for a permit to take water from that source of water supply or from any part of the public water supply system of the applicant supplied in whole or in part from that source. If the department so requires, or if it grants a permit, it shall be the duty of the applicant so to supply water, subject to such requirements as the department may impose. The price to be paid for the amount of water so to be taken may be agreed upon between the applicant and the taker of the water, or if they cannot agree, fair and reasonable amounts and rates shall be, after due hearings thereon, fixed by the public service commission. Any such agreement or determination of the public service commission may from time to time be modified by further agreement between the parties affected thereby or by the further order of the commission.
N.Y. Envtl. Conserv. Law § 15-1521