For almost half of his life, 33-year-old Virender has done a menial job that was traditionally assigned to people like him by India's caste-based Hindu social hierarchy.

Virender belongs to a caste of the most downtrodden Dalit group in the world's second most populous country and has little hope of overcoming the conditions of his birth in his lifetime.

It does not mean he lacks a desire to break free from the system that has condemned him to cleaning sewers manually.

Caste discrimination is illegal in India but you can see it has social acceptance.

Virender, along with hundreds of sanitation workers and their family members, joined a protest march in New Delhi on Sept 25 to demand an end to outdated work practices.

About 1,800 workers have lost their lives, including dozens in Delhi, in the last few years due to dangerous work conditions, according to the Safai Karamchari Andolan (sanitation workers' movement).

Campaigners say municipalities in India still rely on primitive work methods and have called for deploying modern equipment for unclogging drains, cleaning human excreta, sweeping streets and waste disposal.

They say India's advances in space and missile technology mean nothing if scientific achievements don't help the country's most disadvantaged people.

"Other countries have also launched space missions, but they stopped sewer deaths before launching rockets. Why is it that we cannot use modern equipment for cleaning? Is it because this work is done by Dalits?" asked Ashok Bharti, chairman of the All India Ambedkar Mahasabha, an organisation working for Dalit people's rights.

Lawyer Vrinda Grover considers the sewer deaths as "murders" because protective gears are not provided to those who descend into the holes to unclog drains.

She has called for fixing the system that allows such abuse of sanitation workers.

The conditions of those employed by municipal corporations as full-time staff may be slightly better than those who offer services as irregular labourers to private contractors and residential neighbourhoods.

"Every morning I go to a 'chowk' (public square) and wait for work with 50 to 100 others. Those who need our services know where to find us. Sometimes we get work, sometimes we don't," Virender told Bernama.

When he does have work, Virender uses his bare hands and rudimentary tools such as a rod, a rope and a bucket.

Despite his years of experience doing the unpleasant work, he still has his revolting moments.

"When I lower myself into the hole, waist-deep or up to my chest in the dirty water, I don't know what's there. Sometimes a dead rat, human excreta or a tampon gets into my hand. I don't feel like eating food for hours after coming in contact with such things," said Virender, who looks much older than his age and displays a lingering sadness in his eyes.

It is hazardous work for low wages.

Workers have to stand bare-chested in cold water in winter and they suffer unbearable stench. They often fall sick and some die due to illnesses or while on duty.

Those descending into deep pits also face the risk of asphyxiation.

Virender's friend Anil died recently after the rope from which he was being lowered into a 20-feet-deep pit snapped.

"I stopped going to work after that. I was aware of people dying in my line of work, but Anil was like a brother to me. I feel angry, I feel frustrated but I am helpless to do anything about this," Virender said, showing an identity card of his friend.

Anil found his cleaning job an improvement on his previous job as a cycle rickshaw puller, which he had given up as it required more physical strength and a punishing schedule.

Anil's case received wide media publicity, resulting in a public fundraising drive to help his family and galvanising activists who campaigned against manual scavenging, a practice banned by law but still in existence in many parts of India.

Activists say India must get rid of its old mindset and adopt modern practices and reforms for sanitation workers.

"The ruling elites don't feel any pain when people die in sewers. They don't see it as a case of social injustice," Bharti told Bernama.

Participants at the recent march also criticised the government's campaign called 'Swachh Bharat' (clean India), which aims to make the country open-defecation free and create awareness about hygiene, for being discriminatory against the Dalit community.

They point out it encourages more employment of low-caste people in menial jobs, making the social hierarchy further entrenched in India.

Social activist Nikhil Dey said: "The Swachh Bharat mission is creating more casteism because of the way it is planned. It is superficial and does nothing to clean the dirt in the system."