On its journey south and east from the Western Himalayas, through the Gangetic Plain of North India and on to the Bay of Bengal, the Ganges flows for over 2,500 kilometers (1,553 miles). More than 400 million people dwell in its basin and depend on its life source. It's one of the world's 20 largest rivers - and also one of the most polluted on the planet.

In places, the once sacred, life-giving Ganges has become a cesspool, polluted with fecal waste, semi-cremated bodies, and water-borne disease.

In its $3 billion (2.4 billion euros) quest to restore the Ganges to health, the Indian government is turning to an unlikely source - Israel - a tiny, arid Middle East country that is producing world-leading water technology.

Israel NewTech, an initiative led by the Israeli Ministry of Industry, Trade and Labour, is matching Israeli clean-tech companies with Indian partners to tender solutions for the Ganges.

The Indian government aims to have no untreated municipal sewage or industrial runoff enter the Ganges by 2020, but according to Oded Distel, head of Israel NewTech, cleaning the Ganges is more like a 20-year mission.

"It's a huge project. It combines technological aspects and elements from waste water treatment and water management up to irrigation," he said. During dry season, "it becomes more a kind of canal for waste water rather than a real living river."

The World Bank is investing in the clean-up of the Ganges

The World Bank is investing $1 billion (812 million euros) in loans and credits to India, to help with the first step in the Ganges River clean-up. The first goal is to reduce pollution in a sustainable way.

This may mean revolutionary changes to centuries old farming practices in India, where irrigation traditionally relies on the monsoon for flooding, resulting in chemical run-off into the Ganges.

One joint Israeli–Indian company, NaanDanJain, has established a test farm for drip irrigation in India. What is otherwise known as micro-irrigation is an Israeli technology that saves water and fertiliser by allowing water to drip slowly to the roots of plants through a network of valves, pipes, tubing and emitters.

According to NaanDanJain director Amnon Ofen, this technology already started to change the face of Indian agriculture.

"The irrigation business in India these days is above $0.5 billion a year, which in the next two or three years, will reach $1.5 billion - just micro irrigation," he said, adding this would be the reason why foreign companies are based in India.

Bypasses to help save the Ganges

Another Israeli company, bio-engineering firm Water Revive, is looking at natural constructed wetlands as a way to rehabilitate the Ganges. Water Revive marine ecologist Limor Gruber says it involves a series of bypasses, or channels, that divert domestic and industrial waste water from the river to cleanse it naturally, and make it drinkable by the time it flows back into the river. It has been tested successfully on Israel's Yarkon River, where more than eighty bypasses were installed.

"This technology - on the one hand it's sophisticated, but on the other hand it's a part of nature and it needs almost no maintenance. Now, when you go to a third world country and you put pumps, and you need electricity and you need very sophisticated systems, then people don't know how to maintain them," Gruber said.

Figures from India in 2003 show that only 27 percent of India's waste water is treated. According to figures by Israel's national water company Mekorot, 92 percent of Israel's waste water is treated and about three quarters of that re-used for agriculture.

Israel New Tech's Oded Distel says this technology is becoming so advanced that even left-over residue from waste water treatment is being considered as a possible source of energy. He puts Israel's success at water technology down to the fact that it has a 45 percent natural water deficit and must create solutions to sustain the population.

The Ganges River is a spritual place, where people go for ritual baths

"It's an industry that is classically based on 'necessity is the mother of innovation'," Distel said.

Distel also cites flexibility as a reason why Israeli companies are well suited to fashioning solutions for the Ganges. Some of Israel's top information technology professionals translate algorithms designed to analyze information flows into technology that detects water leakages.

"A very important element is the flexibility of Israeli companies to adjust their solution to specific problems. This is something that is unique in the clean-tech arena. The type of water in India is not like in Israel, it's not like [water] in California or in Florida,” Distel said.

As India and Israel celebrate 20 years of diplomatic ties in 2012, Israel NewTech has opened an office in India and an agreement was signed in February, aimed at fostering cooperation with a focus on urban water.

India's ambassador to Israel, Navtej Sarna hopes these business and environmental ties will lead to closer cooperation between the two countries in the future.