LONDON — It is a worldwide emblem of urban life, as ubiquitous as the clutched paper cup of latte or the sight of a pedestrian in rapt communication with the screen of a smartphone. It is the plastic bottle of water, poking from a backpack or grasped in a gloved hand, stacked on the refrigerated shelves of supermarkets, or discarded in the gutter.

There was a time when skeptical old-timers derided bottled water as little more than a marketer’s trick to lure consumers into paying for a liquid that should cost next to nothing. And, equally, there were many people who asked where else they would find water when public drinking fountains had all but disappeared.

But as concerns mount over the detritus of plastics that elude recycling, London’s mayor, Sadiq Khan, let it be known on Monday that he wished to redress the balance by providing more drinking fountains and bottle-filling stations while reducing the prevalence of single-use packaging.

London mayors generally seek to establish a distinctive legacy. Apart from a degree of buffoonery, Mr. Khan’s predecessor, Boris Johnson, who is now Britain’s foreign secretary, made a name in transport, introducing the Boris Bus, a distinctive update on the traditional double-decker, and the Boris Bike, a bicycle for hire on the streets of the capital.