Engaging India is an online column analysing the issues, trends and forces behind the business and politics shaping India and its impact on the world. Engaging India appears on Thursday mornings exclusively on FT.com India , a dedicated online section on India , and is written by Jo Johnson, the Financial Times' South Asia bureau chief; Amy Yee, New Delhi correspondent; and Joe Leahy, Mumbai correspondent.

Bindeshwar Pathak has devoted his life to an unusual cause. In 1970 he founded Sulabh a non-governmental organisation based in Delhi that builds clean toilets for the masses. So far Sulabh has built 1.2m private toilets and 6,000 public ones across India that are used by 10m people each day.

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While this may be the least glamorous of issues, sanitation is vital. In India , the scale of the problem is enormous with about 700m, or about two-thirds of the population, lacking access to modern sanitation and toilets.

This deficit poses serious public health risks. Human waste carries disease yet is routinely dumped into precious water sources or left in the open.

Over half of the world's annual 5m child deaths are linked to poor sanitation and hygiene, said the UN, which has declared 2008 the International Year of Sanitation.

Nearly one-fifth of deaths of children under five are linked to diarrhoea, making it the world's second largest killer of children, after pneumonia.

Dr Pathak reckons that up to 40 per cent of waste produced by Delhi's 16m residents is dumped into the Yamuna River, an especially grim prospect given that it is a tributary of the holy Ganges River where millions of worshippers bathe downstream.

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Rampant water pollution in India continues as details of next year's World Water Forum were unveiled this week at the UN in New York. The annual global water conference highlights UN Environmental Programme predictions that two out of every three people on earth will live in water-stressed conditions by the year 2025 if present patterns continue.

But sewage systems and treatment plants are expensive, highly-complicated infrastructure projects that are out of reach for most of India. Of India's 5,005 towns, only 232 have sewer systems according to Sulabh, which means "simple" in Hindi.

With that in mind, Dr Pathak pioneered a simple, affordable but sanitary toilet for rural areas in 1970 when he was working in Bihar, his home state. During a recent visit to the Sulabh campus on the outskirts of Delhi, Dr Pathak showed me how it works. The well-kept campus houses Sulabh's offices, a quirky toilet museum, a school and training centre for former human waste scavengers, library, research lab and demonstration toilets spread over a concrete lot.

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Dressed in a formal kurta and bandhi vest, the 65-year-old stood at the edge of two circular pits connected to a demonstration squat toilet. He poured two litres of water poured from a bucket into the toilet.

This would flush waste into the pit, which is kept covered with air-tight concrete lids. It takes years for this pit to fill. When it finally fills up, waste is diverted to the second pit. By the time that second pit is full two years later, the waste in the first pit has naturally converted to pathogen-free manure that can be safely removed.

Could it be so simple? Dr Pathak insists it is. More than a million Sulabh toilets have been built across India , some for as little as $35 each. This not only gives people access to a basic service but helps "liberates" low-caste people tasked with manually cleaning and carrying away human waste collected in bucket toilets. "Manual scavenging" was banned by India yet the practice still persists in India.

Dr Pathak's work in sanitation earned him the Padma Bhushan, one of India 's highest civilian honours conferred by the president of India , as well as international awards. His card identifies himself as Sulabh's founder but also as "Action sociologist, social reformer, international expert on low-cost sanitation, public conveniences, biogas from human excreta and rural development."

He has also honed seemingly fantastical technology to create biogas plants that fuel generators, cook stoves and lamps from the (odourless) methane in human waste. Sulabh has built 66 biogas plants in India. The largest is at the Shirdi Sai Baba temple in Maharashtra, which receives 100,000 visitors daily. All of the temple's electricity is generated by biogas from its 120 toilets.

Now Dr Pathak aims to aggressively expand Sulabh toilets in rural areas, as well as other developing countries. The Indian government, through its Ministry of Rural Development, is supporting Sulabh's efforts. But more help is needed to aid the 700m Indians - equivalent to the population of Europe - who lack toilets.

Dr Pathak estimates 13m toilets need to be built in India . To achieve ambitious goals of converting all bucket toilets to the "pour flush" design he pioneered, he admits it is not possible for Sulabh to do it alone.

Sulabh has never accepted foreign aid money or grants in order to retain control over its operations. But now Dr Pathak concedes that social programmes of this scale need external funding.

Sanitation, meanwhile, remains a pressing problem for millions like RP Somdia, a 38-year-old cobbler, who left his village in the desert state of Rajasthan to work in Delhi. He has a degree from the University of Rajasthan yet lives in a jhuggi, or slum, across from the US Embassy. The jhuggi has about 25 toilets for thousands of people who live in the maze of shacks constructed of sticks, mud walls, plastic sheets and corrugated metal.

The 25-year-old jhuggi has had toilets for roughly a decade. What did the residents do before the toilets came? Mr Somdia gestures in the distance to a patch of woods where people still go when they don't feel like queuing up for the handful of toilets.

Sanitation is far more than a matter of convenience. Madhav, my landlord's cook, recently returned home to the poor eastern state of Orissa for the funeral of his 19-year-old niece. Two weeks ago she was stricken by severe "loose motion" and though she was hospitalized, his niece died within three days. It is hard to know exactly what happened but her death is likely related to water and sanitation.

For a country that aspires to be a global power, it is a grievous thing when Indians die for lack of basic services. As Dr Pathak says, sanitation is a human right. Until people are given that right, people like Madhav's niece and her family will continue to suffer.