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Amid the ongoing Maha Kumbh pilgrimage at Uttar Pradesh’s Prayagraj, the debate around the water quality of Ganga river has reignited once again. This time, a Padma Shri awardee scientist has claimed that the holy river has the unique ability to cleanse itself.
On February 21, 2025, the Uttar Pradesh government issued a press release, which cited Ajay Kumar Sonkar who claimed that the purity of the Ganga is still intact.
“Padma Shri Dr. Ajay Kumar Sonkar collected water samples from five major bathing ghats, including the Sangam Noz and Aral (Maha Kumbh city). These samples were sent to his laboratory for microscopic examination. Surprisingly, despite millions of devotees bathing in the river, no bacterial growth was observed in the water, nor was there any decrease in its pH level,” the press statement mentioned.
However, contrary to the Uttar Pradesh government’s claim, a report filed by the Central Pollution Control Board (CPCB) in the National Green Tribunal (NGT) on February 3, 2025, revealed that even on special bathing dates during the Maha Kumbh, high levels of biochemical oxygen demand (BOD) were found in the water at places like Sangam and six other locations. High concentration of BOD signifies that a water body has decaying organic matter in it.
To make things worse, fecal coliform (bacteria found in faeces) was also found to be several times higher than normal standards.
Despite these findings, the UP government’s press statement noted that the Padma Shri awardee scientist’s research showed that the Ganga water contains 1,100 types of bacteriophages. Bacteriophages, or phages, are viruses that specifically infect and destroy bacteria. They are often referred to as ‘bacteria-eating’ viruses because they enter bacterial cells, multiply, and eventually destroy them.
“Due to this self-purification mechanism of the Ganga, the water remained unpolluted even after 57 crore devotees bathed in it,” the state government claimed.
It has long been believed that unspecified bacteriophages exist in the Ganga river and it has been documented in various scientific studies.
The NGT’s judgment on the Ganga case, delivered by Justice S. Kumar on July 13, 2017, mentioned this property of Ganga river several times.
“An ancient medical text, the Charak Samhita, asserts that Ganga water is pure and sacred. It is a major drinking water source, as no germs, bacteria, or fungi can survive in it,” NGT.
The NGT’s judgment cites a study stating, “This is now scientifically proven. Despite some concerns, studies have shown that Ganga can reduce its biochemical oxygen demand (BOD) levels much faster than other rivers. (Refer: D. S. Bhargava, Purification Power of the Ganges Unmatched, LST Bull. 34, pp. 52, 1982).”
The judgment also notes, “Generally, organic matter in rivers depletes the oxygen available and decays slowly. But in the case of the Ganga, an unknown element affects these organic matters and bacteria, destroying them. Due to Ganga’s self-purification properties, its oxygen levels are 25 times higher than other rivers.”
Another study cited in the judgment by the New Delhi-based Malaria Research Centre observed that mosquitoes did not breed in the upper reaches of the Ganga and, when mixed with other water sources, even prevented mosquito breeding.
“The Ganga’s self-purification capacity is due to its extraordinary ability to maintain high dissolved oxygen (DO) levels from its environment. This is why Ganga water is considered sacred. Scientists have studied that Ganga water remains pure when sourced from the river and does not become contaminated even after being stored for years. This medicinal quality is attributed to the herbs and minerals that mix into the water,” the NGT had observed.
The judgment also references a study by British bacteriologist Ernest Hankin in 1896, who documented the presence of powerful antibacterial effects in Ganga water against Vibrio cholera (the bacteria that causes cholera). He suggested that using Ganga’s sacred water could reduce cholera outbreaks.
The National Botanical Research Institute in Lucknow also conducted a study to validate the antibacterial effect of Ganga water on E. coli bacteria.
Even after adding five times more E. coli to the water, it did not affect the natural biological structure of the water. Ganga water was found to destroy E. coli much more effectively than other waters, and even 16-year-old Ganga water was able to eliminate E. coli effectively. This was attributed to bacteriophages, which work similarly to bacteria-eating organisms on E. coli.
These studies claim that Ganga water has unique antibiotic properties, making it highly effective. Given its exceptional liquidity and antibiotic characteristics, it could provide a vital foundation for developing new antibiotics. (Refer: Chandraprakash Nautiyal, Self-Purificatory Ganga Water Facilitates Death of Pathogenic Escherichia Coli O157:H57:311, Current Microbiology (2009) 58:25-29 and in Asia Agri History, Volume 13, Number 1, 2009 (53-56).
Interestingly, the NGT’s judgment (2017) mentions that rivers naturally possess self-purification capacity, mainly due to their flow speed, which maintains the oxygen supply in the water and breaks down organic waste
This means any river with a flow can purify itself. However, the Ganga has been regarded as slightly more effective than other rivers in this regard.
According to the NGT judgment, the Indian government formed a group of secretaries on June 6, 2014, to examine the Ganga rejuvenation action plan.
“Our ancient text, the Brahmanda Purana, clearly mentions how humans should behave on riverbanks. Our ancestors understood the importance of rivers and set guidelines for their preservation. The Ganga’s sacred banks restricted 13 types of activities, including bathing, defecation, water dumping, and throwing discarded flowers. However, present-day practices largely contradict these prohibitions,” the group had told NGT in an official response.
Rivers naturally have the ability to purify themselves, absorbing and treating organic waste. However, in the present context, excessive extraction of water for drinking, irrigation, industries and power generation is deteriorating the water quality of rivers.
With extreme reduction in water flow, especially in dry seasons, the flow of the Ganga has seriously decreased.
The group also mentioned that pollution signals have been seen even in the upper reaches of the Ganga, where its oxygen levels should be maximised.
This suggests that water diversion for hydroelectric projects is damaging the Ganga’s health. Moreover, as the Ganga enters the plains, water extraction for irrigation and drinking needs reaches its peak. The river’s flow, especially between Rishikesh and Prayagraj, almost halts during winters and summers. In other words, the river’s flow stops, but wastewater (sewage) keeps flowing.
The group also identified untreated sewage and solid waste as significant contributors to the Ganga’s pollution.
The NGT acknowledged that all these factors are causing severe water pollution in the Ganga, impacting its self-purification ability.
“If the Ganga continues to flow and its ecosystem is restored on a large scale, it will remain clean on its own and regain those unique characteristics for which the Ganga river is worshiped in India. Joint efforts are needed for purity and uninterrupted flow,” Shashishekar, former secretary in the Ministry of Water Resources, River Development and Ganga Rejuvenation stated.