The water-energy nexus has major implications for the energy sector and national economies going forward. As water becomes scarcer, energy and water efficient technologies become increasingly valuable. 

Overview
Energy producers and long-term investors need to be forward looking with respect to investments in energy plays and technology related to water. Water has and will continue to be crucial for the generation of power and fuel. Regulators are increasingly planning to limit the use of water and incentivize water-efficient technologies. Coal, the most water inefficient energy source, and first-generation biofuels, the most water inefficient fuel source, will be the first targets for water regulation. Proposed policies at the state and federal level address the significance of developing new technologies and maximizing efficiency in water use.

Water withdrawal and consumption by energy source (IEA)