CATHERINE MCGRATH, PRESENTER: Twenty years ago, the practice of manual scavenging, cleaning up human faeces by hand, was outlawed in India.
But disturbingly it still continues in some parts of the country.
It's a task performed solely by the so-called untouchables - the lowest group in India's often-discriminatory caste system
India correspondent Stephanie March reports from Uttar Pradesh.
STEPHANIE MARCH, REPORTER: In Paduri, a small village a few hours drive from Delhi, everyone is getting ready for lunch.
Balah's prepared a modest meal for her sons Pradeep and Kuldeep.
While the boys have spent the morning at school, Balah's been doing something most people would deem unthinkable. She's a manual scavenger, someone who removes human waste from dry toilets that are not connected to a sewerage system.
(Footage of Balah going about her work plays)
BALAH (translation): Earlier I used to work in almost 20 houses but now the work is less. I still have 10 houses to clean.
STEPHANIE MARCH: Every day she goes from house to house cleaning up after other people by hand. Her mother in law, Shakundulah (phonetic), has been doing the same work for 40 years.
Balah was forced to take on the job when she married into the family. The women get paid about $2 a month for each house they clean and sometimes they're not paid in cash at all.
BALAH (translation): I've been working for the same households for 15 years but if I ask for food, they will not give me fresh food, just the leftovers.
STEPHANIE MARCH: The work that Balah and people like her do is not just demeaning. Activists say it encourages the oppression and discrimination brought about by India's caste system.
Balah and the others who live in her settlement on the outskirts of the village are Dalits, members of India's lowest caste and often referred to as untouchables.
Oxford scholar Agrima Bhasin, from the Centre For Equity Studies, has been following their plight for years.
AGRIMA BHASIN, SCHOLAR: The upper caste feel that the lower castes are meant to do this work and will do this work for the rest of their lives.
STEPHANIE MARCH: But India's constitution prohibits discrimination based on caste.
Manual scavenging was banned in India in 1993, but the practice survives in parts of the country.
BEZWADA WILSON, MOVEMENT OF MANUAL SCAVENGERS: It is estimated we are expecting even now 300,000 still in the manual scavenging.
STEPHANIE MARCH: Bezwada Wilson was born a Dalit. His parents were manual scavengers. For the past 30 years he's led an organisation called the Movement of Manual Scavengers, or SKM.
It's largely thanks to his efforts the practice was outlawed 20 years ago.
BEZWADA WILSON: Thinking of equality in India is very difficult, because of this strongly believed majority here that all are equal but some are more equal.
STEPHANIE MARCH: Lawyer Shomona Kannah has been fighting in the Supreme Court to try to force state governments to comply with the law that prohibits manual scavenging.
SHOMONA KANNAH, LAWYER: We're talking about the exclusion of an entire people, by the fact of their birth into a particular caste or in a particular family, from a whole range of rights as citizens, as free citizens of a free country. And why is that? Because by their ethnic origin or the fact they're born into a particular caste group, they're considered dirty
STEPHANIE MARCH: The Indian government offers financial assistance in the form of a loan for Dalits wanting to get out of manual scavenging. But activists say that's not enough.
AGRIMA BHASIN: As far as rehabilitation is concerned, I think we need to go beyond the economic to include social and psychological rehabilitation for the manual scavengers to restore their lost dignity.
BEZWADA WILSON: This is a national shame. It is a blot on the society.
STEPHANIE MARCH: A blot on society and some say a blot on India's entire development story.
AGRIMA BHASIN: Your story of growth is a story of exclusion. You're a nation that is successively trying to hide its underbelly and you're building your foundation on a weak morality.
STEPHANIE MARCH: Bezwada Wilson and those fighting to liberate manual scavengers say until upper castes accept and practice equality in its true sense it's unlikely the plight of Balah and those like her will change.