N.Y. Gen. Mun. Law § 118-a

§ 118-a. Contracts. Any municipality authorized herein to develop a\nsupply of water for sale is hereby empowered to enter into contracts for\nsuch periods as it may deem necessary but not in excess of forty years.\nSuch contracts may contain provisions for establishment and revision of\ncharges for water, for adjudication of disputes and, in return for a\nguaranteed minimum consumption by the purchaser, for the application of\nconservation methods by the seller when necessary to preserve such\nexcess.\n