The Water That Would Not Spoil: Ganga Jal Between Faith and Microbiology

The pot on the shelf

In many Hindu homes, there is a small sealed vessel that nobody opens casually. It holds Ganga jal, water carried back from Haridwar, Rishikesh, Prayagraj or Varanasi. It sits in the prayer room for months, sometimes years. A few drops are sprinkled to purify a new house, added to the water of a ritual bath, or placed on the lips of someone who is dying.

Ask about it, and you will usually hear the same claim: Ganga water never spoils. Ordinary water kept that long turns green, smells, grows slime. Ganga water, people say, stays clear.

It is easy to dismiss this as faith talking. It is harder to dismiss once you learn that the claim was tested scientifically more than a hundred and twenty years ago, and that the test pointed to something real: a hidden army of microscopic predators living in the river. The discovery of that army helped open an entire field of biology, and it may yet help save lives in an age when antibiotics are failing.

But this is a journal that sets the legend beside the evidence, and the evidence here cuts both ways. The same river that holds those natural guardians also carries some of the heaviest pollution of any great river on Earth. To understand Ganga jal honestly, we have to hold both facts at once.

An emperor's water and a sailor's cask

The reputation is old. According to Abul Fazl's Ain-i-Akbari, the chronicle of the Mughal court, the emperor Akbar called Ganga water the "water of immortality" and drank it both at home and on his travels, having it carried to him in sealed jars wherever he was.

Later accounts, many of them repeated without clear sources, say that sailors on ships leaving Bengal preferred to fill their casks from the Hooghly, a branch of the Ganga, because its water stayed sweet longer on the voyage than water taken from other rivers. Those stories are hard to verify, and they should be treated as tradition rather than evidence.

What matters is that the belief was widespread, practical and specific. People were not only saying that the river was holy. They were saying that its water behaved differently: that it resisted the rot that every traveller in a hot climate knew too well. That is a claim that can be tested.

A chemist on the ghats

In the 1890s, India was struggling with repeated outbreaks of cholera, a disease caused by the bacterium Vibrio choleraeVibrio cholerae The bacterium that causes cholera, spread through contaminated water. that spreads through contaminated water and can kill within a day. Ernest Hanbury Hankin, a British bacteriologist working as the government's chemical examiner in Agra, was studying how cholera moved along India's rivers.

He noticed something puzzling. Cholera did not seem to spread down the Ganga and Yamuna as readily as he expected, even though bodies of cholera victims were sometimes placed in the water. So he went to the laboratory.

In 1896, Hankin published his results in the Annales de l'Institut Pasteur, one of the leading medical journals of the day. He reported that water from the Ganga and the Yamuna could kill cholera bacteria within a few hours. Water from wells did not. The killing power survived when the water was passed through a fine porcelain filter that removed all known bacteria, so the active agent was something smaller than a bacterium. But it was destroyed when the water was boiled.

Hankin could not identify what the agent was. He had no microscope powerful enough to see it. But he had shown that the old belief pointed to something physical: there was something in the river water, invisible and heat-sensitive, that attacked bacteria.

The invisible hunters

Twenty years later, the mystery was solved. In 1915 the English bacteriologist Frederick Twort described a transmissible agent that destroyed bacterial colonies. In 1917, working independently in Paris, the French-Canadian microbiologist Félix d'Hérelle described the same kind of agent and gave it the name that stuck: bacteriophagebacteriophage A virus that infects only bacteria. The name means “eater of bacteria”., "eater of bacteria".

Bacteriophages, or phages for short, are viruses that infect bacteria and nothing else. They cannot infect human cells. A typical phage looks like a tiny lunar lander: a head packed with genetic material, sitting on a tail with legs. It lands on a bacterium, injects its genes, and turns the cell into a factory that builds new phages. Within an hour or less the bacterium bursts open, releasing a fresh swarm of phages to hunt the next victim.

Phages are the most abundant biological entities on the planet. Estimates suggest there are around ten phages for every bacterium on Earth, and the total number runs to roughly 10³¹, more than the number of stars in the observable universe. Wherever bacteria live, in soil, oceans, sewage and our own gut, phages live alongside them, keeping their numbers in check.

Many microbiologists now believe that Hankin's mysterious agent was a population of phages. They pass through filters that stop bacteria. They are destroyed by boiling. And they are specific: a given phage usually attacks only one kind of bacterium, which fits with Hankin's observation that the river water killed cholera bacteria in particular.

D'Hérelle himself was drawn to India by the story. In the late 1920s he worked on cholera here, isolating phages and testing whether they could be used to treat and prevent the disease. Treating infections with phages became known as phage therapy.

Why the Ganga is rich in phages

Here is the twist that makes this story so interesting. Phages are abundant where their prey is abundant. A river that carries a great deal of bacteria, from human waste, decaying organic matter and dense human settlement along its banks, tends to carry a great many phages too.

In recent years, studies carried out for the government's clean Ganga programme by India's National Environmental Engineering Research Institute (NEERI) have reported a high abundance and diversity of phages in Ganga water and sediments, and have suggested this as one reason the water resists putrefaction during storage. Researchers have also pointed to the river's sediments, its dissolved oxygen and its mineral content as possible contributors.

So the river's famous self-protecting power is real in part. But it is not the sign of a pristine river. It is the sign of a living, crowded one, where bacteria and their hunters are locked in a constant war.

The vessel matters too

Look at how Ganga jal is traditionally kept: very often in a sealed vessel of copper or brass. That detail turns out to matter.

Copper is toxic to many microbes, a property scientists call the oligodynamic effectoligodynamic effect The way very small amounts of some metals, copper and silver among them, kill microbes., in which very small amounts of certain metals kill bacteria. In a study published in 2012 in the Journal of Health, Population and Nutrition, researchers stored water deliberately contaminated with disease-causing bacteria, including E. coli and Vibrio cholerae, in copper pots at room temperature. After sixteen hours, the bacteria could no longer be detected, while the same water stored in plastic or glass remained contaminated.

A tightly sealed pot also matters. Algae, the usual cause of water turning green, need light. Many of the organisms that make stored water smell need fresh supplies of nutrients and oxygen from outside. A small, dark, sealed copper vessel is hostile to almost all of them.

In other words, the traditional way of keeping Ganga water may contribute as much to its long shelf life as the water itself. The ritual practice and the microbiology point the same way, even if the people who designed the practice could not have known why it worked.

A river that cleans itself?

A second popular claim says that the Ganga "purifies itself" much faster than other rivers. This one is often quoted with dramatic numbers, such as "twenty-five times faster".

The claim seems to grow out of real research, including studies in the 1980s by D. S. Bhargava and colleagues, who measured how quickly the Ganga broke down organic waste and absorbed oxygen in particular stretches. They reported that the river could recover from organic pollution unusually quickly in those reaches. Large, fast-flowing, turbulent rivers can mix oxygen into their water rapidly, which helps bacteria and other organisms consume waste.

But the dramatic multiplier is not a single, well-established figure that applies to the whole river at all times. It is a selective summary of specific measurements, made decades ago, in specific stretches, under specific conditions. It certainly does not mean the river can absorb unlimited sewage. That leads to the uncomfortable half of this story.

The other half of the truth

The same Ganga that produced Hankin's discovery is today one of the most heavily burdened rivers in the world. More than 400 million people live in its basin. Along its course, untreated or partly treated sewage, industrial effluent and agricultural run-off enter the river.

Monitoring data from India's Central Pollution Control Board have repeatedly shown that, in many stretches, the level of faecal coliform bacteria (a standard indicator of sewage contamination) exceeds the limits considered safe for bathing, sometimes by a very large margin. Phages attack particular species of bacteria. They do not make sewage safe, and they do nothing at all against chemical pollutants, heavy metals or plastics.

There is an even more worrying finding. In 2014, researchers from Newcastle University in the United Kingdom and the Indian Institute of Technology Delhi measured genes that make bacteria resistant to powerful antibiotics in the upper Ganga around Rishikesh and Haridwar. They found the levels of one such gene, blaNDM-1blaNDM-1 A gene that lets bacteria resist carbapenems, among the last antibiotics doctors can turn to., rose sharply during the peak pilgrimage months, when millions of visitors come to bathe, compared with the rest of the year. The faithful who come to be purified by the river were, without knowing it, contributing to the spread of resistance genes that threaten all of us.

That is not a reason to abandon the tradition. It is a reason to take it seriously. A river considered a goddess is a river that should be protected, not used as a drain.

The claims, checked

The claim	Verdict	What the evidence shows
"Ganga water never spoils when stored."	Partly true	Stored Ganga water often resists putrefaction, probably helped by bacteriophages, sediments and minerals, and strongly helped by storage in sealed copper or brass vessels. It is not immune to contamination.
"Ganga water kills bacteria."	Partly true	In 1896, Ernest Hankin showed that Ganga and Yamuna water killed cholera bacteria in the laboratory. The agent was very probably bacteriophages, which attack specific bacteria, not all of them.
"Ganga water is pure and safe to drink straight from the river."	False today	In many stretches, faecal coliform levels exceed bathing limits. Phages do not remove sewage, chemicals or heavy metals.
"The Ganga purifies itself twenty-five times faster than other rivers."	Overstated	Based on selective older measurements in particular stretches. Fast, turbulent rivers do recover from organic waste quickly, but no single multiplier applies to the whole river.
"Bathing in the Ganga cures disease."	No evidence	No clinical evidence supports this. Bathing in contaminated water carries real risks of infection, and pilgrim crowds have been linked to rising antibiotic-resistance genes.

From the ghats to the hospital

The story does not end in the nineteenth century. It may matter more now than ever before.

For most of the twentieth century, antibiotics made phage therapy seem unnecessary in the West. The Soviet Union kept the idea alive: the Eliava Institute in Tbilisi, Georgia, which d'Hérelle helped to found in the 1920s with the Georgian microbiologist George Eliava, still treats patients with phages today.

Now the world faces a crisis of antibiotic resistance. Bacteria are evolving faster than new drugs are being developed, and infections that were easily cured a generation ago are becoming deadly again. Phages are back on the research agenda. In 2019, doctors in the UK and scientists in the United States reported treating a teenage cystic fibrosis patient, Isabelle Carnell-Holdaway, whose life-threatening drug-resistant infection was brought under control with a cocktail of genetically engineered phages, the first reported use of engineered phages in a human patient. Clinical trials of phage therapy are now under way in several countries.

Seen in that light, Hankin's afternoon on the riverbank in Agra takes on a remarkable shape. A traditional belief about a sacred river pointed a scientist towards an invisible natural defence. A century later, that same kind of defence may help us survive the age of superbugs.

A myth half-proved, and a warning

So, is the legend true?

Half of it is. There really is something in Ganga water, very probably a rich population of bacteriophages, that attacks bacteria and helps the water resist decay. The traditional practice of storing it in sealed metal vessels adds a second, independent protection. Generations of families who kept a pot of Ganga jal on the shelf were not imagining what they saw.

The other half of the legend, the idea that the river is therefore pure and can absorb anything, is not just wrong. It is dangerous. The phages thrive precisely because the river is crowded with bacteria. Their presence is a sign of how much life, and how much waste, the river carries.

Perhaps the truest reading of the old belief is not "the river cannot be harmed", but "the river is alive". Living things can heal themselves within limits, and can be overwhelmed beyond them. The Ganga's microscopic hunters have been fighting on our behalf for as long as people have bathed in her waters. The least we can do in return is stop making their battle impossible.