Imagine a mother in a rural village drawing water from a well with her pitcher. This seemingly ordinary water holds her family’s future — for drinking, cooking and bathing. But beneath the surface lurks a hidden threat: contamination by arsenic, salinity and heavy metals, silently poisoning the lifeline for millions in Bangladesh.

Despite 98% of people having water access, only 59% enjoy safe drinking water that meets quality standards. This leaves 68.3 million people vulnerable to illnesses and developmental issues. Moreover, just 15% of the population has piped water, with the poorest hit hardest, according to a report by the World Health Organization (WHO) and UNICEF’s Joint Monitoring Programme.

To understand the problem, in 2020 the Bangladesh Water Development Board (BWDB) a vast project. Equipped with 901 monitoring wells, including those plunging to depths of 1,100 feet, the project exposed a disconcerting reality throughout the 2020-21 monsoon and dry seasons. Anwar Zahid, BWDB’s director of groundwater hydrology, revealed alarming arsenic levels just below the surface, surpassing safe limits, notably in floodplains and deltas.

“Bangladesh’s acceptable limit for arsenic is five times higher than the WHO standard — 50 micrograms per liter [µg/L]. Water samples analyzed indicated levels below this limit, but certain regions exceeded 10 µg/L standard, reaching an alarming 311 µg/L in Shariatpur,” he said, .

“Areas of particular concern include flood plains and delta areas, excluding , Madhupur Garh and Teesta Fan regions, where arsenic levels are alarming at depths below 50 meters [164 feet],” Zahid told Mongabay.

Arsenic in groundwater, found naturally worldwide, is harmful when consumed through contaminated water used for drinking, cooking and crop irrigation. Long-term exposure can lead to serious health issues like cancer, skin problems, heart conditions and diabetes and impact cognitive development and young adult mortality, according to WHO.

Bangladesh heavily relies on well water for drinking, with nearly half of wells exceeding safe arsenic levels. With rising sea levels due to climate change, scientists say they worry that this problem could get worse.

In a new study published earlier this year, researchers suggest that as sea levels rise, aquifer conditions change, releasing more arsenic into well water. This happens due to reduction processes and the salt effect, making the arsenic more soluble and potentially more harmful.

“These changes in aquifer chemistry are expected to increase the release of arsenic into Bangladesh’s drinking well water by reduction and by the salt effect. Finally, this increased exposure to arsenic is expected to increase the rates of death and disease from chronic arsenic poisoning,” the study reads.

Salinity, heavy metals bring double trouble

The predicament intensifies in the 19 coastal districts of Bangladesh, where the only respite from salinity lies in deep aquifers, plunging around 300 meters (984 feet) below the surface.

Close to the sea and extending inland to Gopalganj district , salinity levels surge to three times the safe limit, registering a staggering 3.0 parts per thousand (ppt).

However, the most alarming revelation unfolds in Satkhira, , where shallow water samples from Ashashuni exhibit salinity levels soaring as high as 40.0 ppt — equivalent to seawater.

“Yet, the challenges, a glimmer of hope persists. There are still pockets of freshwater within these salinity-ridden zones. Additionally, the monsoon season offers a brief respite, with slightly lower salinity compared to the dry season,” Zahid said.

Researchers studied eight physical and 19 chemical elements in Bangladesh’s groundwater, cross-verified through extensive lab testing in the United States and Germany.

While drinking water ideally should have no more than 1.0 mg/L of mineral iron, due to elevated levels in groundwater, up to 5.0 mg/L is deemed safe in Bangladesh.

During the rainy season, mineral iron levels ranged from 1.0-5.0 mg/L, spiking to 21.7 mg/L in the dry season, especially in upper aquifers, according to the BWDB study.

Manganese levels in some areas exceeded the 0.3 mg/L safe limit, raising concerns, as emphasized by Zahid. Excessive aluminum, iodine and boron were also found in various water samples at different locations and depths.

Development success threatened by dry wells and climate woes

In the pursuit of progress, Bangladesh faces a critical hurdle: the draining of its groundwater reservoirs. Scientists attribute this to intensive irrigation and the impacts of climate change.

Despite impressive economic growth, particularly in agriculture, with nearly doubled rice productivity since 1990, a 2022 study in the journal Nature reveals a downside.

Intensive groundwater use for irrigation, especially in dry seasons, poses a significant challenge. Additionally, pollution from industrial and domestic sources compounds the risk.

Satellite data analysis reveals a significant depletion of 37.5 billion cubic meters (1.3 trillion cubic feet) in terrestrial water storage across Bangladesh since 2002, mainly attributed to irrigation practices.

In northwestern regions and metropolitan Dhaka, aquifers have dropped by about 1 meter (3.3 feet) annually since 2000, according to the study. “Farmers now pump groundwater from 20 metres [65.6 feet] deeper than they did two decades ago,” the study notes.

Citing the study results as a wake-up call for Bangladesh, Robin Kumar Biswas, co-author of the study and BWDB superintending engineer, emphasized that the nation’s current water management predominantly centers around agriculture. He stressed the necessity to address the existing strain on groundwater for sustainable usage.

“As Bangladesh aspires to achieve developed status by 2041, there is a critical need to shift focus cash crops and alleviate the pressure on groundwater,” Biswas told Mongabay.

The study highlights that climate change adds complexity to Bangladesh’s water supply, increasing the probability of extreme rains. Despite this, satellite data surprisingly indicate a 10% decrease in annual rainfall rates over the past two decades.

Looking beyond Bangladesh, an analysis of river-gauge data demonstrates a significant 50% reduction in the combined winter water flow from the Ganges, Brahmaputra and Meghna rivers between 1993 and 2021.

This decline is linked to diminished rainfall and increased groundwater extraction for agriculture upstream in India, the study underscores.

Bangladesh launches bold initiatives to tackle water woes

In a bid to combat widespread water challenges, Bangladesh has rolled out a series of initiatives, anchored by the National Water Policy, advocating equitable access to clean water for all.

Backed by a substantial $1.8 billion, the government’s Arsenic Risk Reduction Project the arsenic crisis. It prioritizes fixing contaminated tube wells, providing safe water and fostering awareness through local governance.

The project director, Bidhan Chandra Dey, said the situation of arsenic pollution has improved a lot in the last 20 years. The number of shallow tube wells has decreased. People are more aware of arsenic than ever before.

In a positive trend, the country has witnessed a continuous rise in clean water access from 2016 to 2020. Statistics show an annual increase, ranging from 0.42-0.47%, reflecting the nation’s efforts toward enhancing clean water availability for its citizens.

Rainwater harvesting systems, introduced collaboratively by the government and the United Nations in coastal regions, serve as a vital resource for families facing water scarcity. This initiative, aimed at aiding mothers in water collection, enables them to store an ample supply during the rainy season, ensuring sustainability during dry periods.

Experts recommend enhancing these rainwater harvesting systems to alleviate the strain on agricultural water resources. They propose a shift from water-intensive rice cultivation to more water-efficient crops such as wheat and legumes.

Additionally, they stress the importance of minimizing arsenic in groundwater by significantly reducing the excessive use of nitrates and pesticides for a more sustainable environment.

With a vision for sustainable development amid climate change, in 2018, Bangladesh unveiled the Bangladesh Delta Plan 2100. While addressing water security, the plan demands substantial investments and further research.

Bangladesh demonstrates strong political will in addressing water insecurity challenges. Success hinges on a thorough understanding of water systems, emphasizing high-quality, openly accessible data, research initiatives and increased funding for infrastructure, as emphasized by experts in the field.

Banner image: A farmer irrigating a rice field. Image by Mahadi Al Hasnat.

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Citations:

Frisbie, S. H., Mitchell, E. J., Molla, A. R. (2024). Sea level rise from climate change is expected to increase the release of arsenic into Bangladesh’s drinking well water by reduction and by the salt effect. PLOS ONE. doi:1371/journal.pone.0295172

Getirana, A., Biswas, N. K., Qureshi, A. S., Rajib, A., Kumar, S., Rahman, M., & Biswas, R. K. (2022). Avert Bangladesh’s looming water crisis through open science and better data. Nature. doi:10.1038/d41586-022-03373-5