Amr bin Dinar (may Allah have mercy on him) said that selling surplus water has been forbidden. Abu al-Minhal (may Allah have mercy on him) said that Iyas bin Abd (may Allah be pleased with him) said to the people: "Do not sell water that is surplus to need, for the Messenger of Allah (peace and blessings be upon him) forbade it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 11058