City authorities had red-flagged the century-old building in the megacity’s bustling Grant Road area for repairs three years ago.

The government issued a “warning notice for evacuation” in June – but residents ignored it.

“No one vacated the premises”, the state housing authority said.

When the building collapsed, one passer-by was killed, four were injured and the fire brigade had to rescue 13 people trapped inside.

Vaishnav Narvekar, who ran a simple cafe on the ground floor, said he had been “expecting” it to collapse – just not so quickly.

It was the “worst feeling”, he said.

But that is only one case among many in the densely populated city of about 20 million people.

More than 13,000 buildings require “continuous repair” to stave off collapse, the state’s Maharashtra Housing and Area Development Authority (MHADA) said.

Of those, it lists nearly 850 buildings as being “dangerous and dilapidated” and “not recommended for repair”.

Many are blocks of flats packed with residents, suggesting more than a hundred thousand people could live in buildings at risk.

Scores are crushed to death each year when buildings collapse, their walls weakened by rainstorms which climate scientists say are increasing in intensity.

Mumbai, the home of glitzy Bollywood stars and billionaire tycoons, is in the midst of a major infrastructure drive, including highways, metro lines and bridges.

But the government says its affordable housing budget is stretched, leaving many tenants determined to stay put in unsound dwellings.

“Where should we go if we left?” asked one tenant in the suburb of Ghatkopar, in a building listed as “dangerous”, asking not to be named for legal reasons.

“Our lives are here.”

Mumbai has the highest rental rates in India, with the median rent for a one-room flat estimated at US$480, according to the Global Property Guide.

Top-end rents can be a dozen times higher.

Owners complain restrictive rent control laws mean some long-term tenants pay legacy rent fees far lower than market rates, so they do not have the funds to invest in repairs.

Tenants fear landlords will evict them, promising compensation, and then fail to pay.

“Builders who will profit from redevelopment need to make sure we are adequately compensated,” added the tenant, who pays 800 rupees (US$9.50) for a 46-square-metre (500-square-foot) flat.

In a three-storey building in Ghatkopar classified as “dangerous”, Jayesh Rambhiya rents a small flat for around 500 rupees a month.

Rambhiya, who grew up in the building, said he would consider leaving if offered compensation since he’d have to pay around 10 times more for a similar flat nearby.

“This is our right,” he said.

City authorities offer temporary “transit housing” for those waiting for their home to be rebuilt, but space is severely limited.

Sanjeev Jaiswal, the MHADA housing authority’s deputy head, said they were “almost” full.

Near Grant Road – where the building collapsed in July – is another four-storey block of flats. It is also on the “most dangerous” list.

Farida Baja, who runs an animal shelter in the building, received an evacuation order in June.

“This is a very strong building,” she said, shrugging off her failure to find new accommodation.

“Even when we have to put a nail in the wall, the nail doesn’t go in.”

Another tenant had since won a temporary court order staying demolition.

Some residents accuse developers of claiming buildings are worse than they are to force tenants out.

Residents therefore use legal challenges to delay demolition for years.

Baja believes the surveyors are wrong, tapping the condemned walls with confidence.

“I am not afraid,” she said. “I know the building is not coming down”.