(CNN) -- Jockin Arputham has been a slum dweller for 43 years, one of more than a million across India.
He shares a 30-hectare (72-acre) plot of land on the outskirts of Mumbai with about 70,000 other people, with communal toilets and self-built homes.
Arputham, 64, started advocating for rights for slum dwellers 40 years ago when he was threatened with eviction.
"How could I be silent when my slum was going to be demolished and we were going to be made homeless?" Arputham explained to CNN.
Arputham is now the president of Slum Dwellers International, a confederation of urban poor in 28 national organizations, and his campaign is as relevant as it was 40 years ago.
A third of the urban population in developing regions lives in slums, according to U.N. Habitat, the United Nations department that focuses on urban development.
How to handle these makeshift settlements -- which often are overcrowded, lack adequate water supply and sanitation and whose residents' land rights are usually insecure -- is a challenge facing cities around the world.
It's a problem that isn't going away. U.N. Habitat forecasts that the number of slum dwellers in the world will grow by 6 million a year and reach 889 million by 2020.
"First of all, city authorities need to acknowledge they have a slum problem and set targets for how to reduce it," said Eduardo Moreno, head of U.N. Habitat's Global Urban Observatory.
"Many cities automatically respond that they don't have slums or that they are very small, but data from U.N. Habitat shows it's more than the city authorities like to believe".
Moreno says governments need to invest heavily in reducing urban poverty and involve communities in their programs to improve slum conditions.
CNN
