“Climate change plus growth equals an existential threat,” Mr. Bevan said.
To avoid severe water shortages, he added, demand would have to be reduced — by taking measures like cutting down on leakage, increasing metering, having sustainable drainage systems and cutting down personal use — and the supply would have to be expanded.
“We can increase supply by a mix of methods, all of which we’ll need to pursue,” Mr. Bevan said. Those include building more desalination plants, transferring water from surplus to deficit areas and building reservoirs, he added. The last reservoir built in Britain is several decades old, he pointed out.
Michael Roberts, chief executive of Water UK, an organization that represents British water companies, agreed that multiple steps needed to be taken.
“A twin-track approach is the right way to go, reducing demand for water at the same time as increasing supply to deal with the challenges of growth on the one hand and climate change on the other,” he said in a statement Tuesday.
Mr. Roberts added that “water companies have publicly committed to cut leakage by 50 percent by 2050” and underlined the need for the government, industry and regulators to work together.