Which London Underground line is known by the nickname “the Drain”?

The Waterloo & City line is known by the nickname “the Drain.”

The name reflects the line’s short route beneath the River Thames between Waterloo and Bank. It was built primarily to carry commuters from the main-line railway terminus at Waterloo into the City of London’s financial district. Because the railway is short and largely underground, the nickname became a longstanding piece of London transport slang.

The line opened in 1898 and was originally operated by the Waterloo & City Railway. It was later absorbed into the Underground system and became part of London Transport. Unlike most Underground lines, it has no intermediate stations.

The Waterloo & City line operates mainly on weekdays and has historically had a different service pattern from the rest of the network. Its short length makes it easy to overlook, but it is an important commuter link.