Britain Comes to Terms With Its New Water Poor Reality

It’s approaching midnight on a leafy, residential street in southeast London, and Stewart Knowles is listening for water. Bent sideways, with a focused expression, he leans his head on a stick, like a doctor with a giant stethoscope, detecting the telltale wish-washing noise that suggests a pipe is leaking. “I’ve always described it as like a shell when you put it to your ear,” he says.

Knowles manages a team of London water utility workers who solve drippy mysteries in the city’s underground pipes and tunnels. His employer, Thames Water, knows how much water should be used by its ...