Water scarcity used to sit in environment ministries. Increasingly it appears in treasury documents, because the costs of shortage are showing up in electricity generation, agriculture and industrial output.
Hydropower is the clearest example. When reservoir levels fall, generation falls with them, and the replacement is almost always more expensive and more polluting.
Agriculture is the larger consumer, and the most politically difficult to reform. Irrigation subsidies are widespread, popular and frequently structured to reward the heaviest users.
The policy tools are unglamorous: metering, tariff reform, leak repair and storage. They are also cheaper than the emergency responses that follow a bad year.
