Chapter 9 of the NGFS Case Studies book analyzed the effect of water shortages on different companies in the mining, power generation, and beverage industries by applying a "shadow water price" to the amount of water used. The shadow water price is based on what the price of water should be given its economic value. It was calculated for different regions of the world based on availability and use of water, and then allocated to different companies based on the locations of their operations. Surprisingly, it found a much greater impact on mining and power generation companies than beverage companies. Because of the higher operating costs from higher water prices, the Net Debt/EBITDA increased by 2x to 3x for BHP Billiton, Glencore, and Rio Tinto (mining), Eskom and Sempra (power generation), and Femsa (beverages), putting their debt into non-investment grades.