Image caption Many widows are abandoned in Vrindavan where they live off charity while they wait to die

The Hindu temple town of Vrindavan, a few hours south-east of Delhi, is known by another name locally: it's called the city of widows.

While most come here to find religion, many come because they have nowhere else to go. Others are just dumped here by families who no longer want to pay for their care.

Almost all of them are widowed women.

Image caption Shakti Dasi had nowhere else to go

Sixty-five-year-old Shakti Dasi from Agartala in north-eastern India is one. She came here eight years ago when her husband died.

Her sons no longer want her, she says.

"It's a struggle to survive, but I can manage on very little. Like everyone else, I too hoped that my children would grow up to take care of me, but they didn't. So I had no choice but to come here."

Ostracised

India is home to an estimated 40 million widows - approximately 10% of all women.

Ageing women are more vulnerable than men. Without any financial security or welfare infrastructure, many of them are abandoned in Vrindavan- where they live off charity while they wait to die.

Shakti Dasi and other widows like her chant prayer songs twice a day, four times a week to earn 20 cents and a bowl of rice.

How can someone getting 300 rupees, or less than $5, survive? Winnie Singh, Maitri

Considered inauspicious, widows are ostracised by many and have few sources of income.

Helping these women with their finances are non-profit organisations such as Maitri.

"The social welfare system in India is practically non-existent," says Winnie Singh, the founder of Maitri.

All widows over the age of 60 are eligible for a small government pension worth less than $5 (£3) a month.

Image caption Winnie Singh of Maitri (right) founded Maitri to help widows with their finances

But most are illiterate and do not have bank accounts to access even that.

"How can someone getting 300 rupees, or less than $5, survive?" says Ms Singh.

"How are they going to hire a room to live, buy rations etc? Even if you give them a below-the-poverty-line card, that doesn't give them anything free."

Growing anxiety

Overall, India remains a young country. The elderly account for just 9% of the population.

But the number of old people is rising steadily. The UN warns it could triple, reaching 300 million within the next 40 years.

Media playback is unsupported on your device Media caption Watch: India’s growing population of elderly people with no family to fall back on

In a nation without social security and state healthcare, there is growing anxiety about how India will care for its elderly.

Nearly 90% of the country's workforce is in the informal sector. They are mainly self-employed, low-income workers who do not have any access to pension schemes.

So that puts them in a particularly vulnerable position where they could easily sink below the poverty line in their old age.

Many doubt whether the country's current infrastructure can keep up.

"One step could be, can you establish a subsidy mechanism for screening or providing some medication for these people? That could have a certain cost," says Amit Mookim, head of healthcare at KPMG.

Image caption India has an estimated 40 million widows

"Then, is there a mechanism to take care of certain procedures, operations or surgeries which is then contracted to private players? That is another cost.

"Then there is the end-of-life care for which the infrastructure doesn't exist - so how much infrastructure can you build?"

Experts feel that the lack of a nationwide social security system poses a serious risk to the economy.

In Vrindavan, some non-profit organisations are tackling the problem of food and healthcare at a micro level.

At Maitri's centre, about 500 widows converge at midday for a free hot meal.

They are given health advice and free medicines as well.

With families struggling to care for their elders at home, the plight of these women is likely to become increasingly common.

But for now, neither the government nor the private sector have any simple solutions to offer.

And for some, like Shakti Dasi, it may already be too late.