This document discusses water efficiency and treatment for chillers, data centers, and hospitals. It notes that current water practices are unsustainable given drought conditions, and that traditional water treatment focuses more on product sales than efficiency. A new approach called Nereus uses online monitoring of water chemistry and system performance to optimize cycles of concentration, minimize water and chemical use, reduce scaling and corrosion, and lower energy costs. Implementing this approach could save over 1 billion gallons per year across industries that rely on water-cooled chillers.