The young man swings the sodden red garment around his head and thrashes it against the flogging stone before it is spun and hung out to dry in the fierce Indian sun.

This is Mumbai's Dhobi Ghat, known as the world's largest outdoor laundry, where hundreds of traditional washermen hand-clean the teeming city's dirty clothes.

Built under British colonial rule and now a popular tourist attraction, Dhobi Ghat is integral to Mumbai's daily life with the laundry even picked up and delivered fresh to the doors of its countless customers.

Last year the site set a Guinness World Record for the "most people hand-washing clothes simultaneously" at a single location -- 496 "dhobiwallahs" washed their way to the title.

But its prime position in the city has caught the eye of ambitious property developers, while the rising popularity of washing machines is threatening the livelihood of dhobiwallahs, who earn less than $10 a day.

Many of those who can afford it have bought their own machines and for now the 25-acre hub shows little sign of slowing down, as the latest daily batches arrive for a beating to remove the grime of the city.