Bengaluru: If reports that nearly half of India’s groundwater has depleted shocked its population last month – with one-third of the country reeling under drought — contamination of whatever water is left is affecting half of India, as on April 26, 2016.

According to information obtained from the ministry of water resources, groundwater in 320 of 640 districts in the country is contaminated by fluoride, arsenic and other chemicals, and heavy metals like lead and chromium, which the ministry of drinking water and sanitation says, affects 6 lakh habitations directly and many more indirectly.

In Karnataka, for example, 29 of 30 districts reported groundwater contamination in 2015-16, up from 21 the previous year, while 30 districts of Maharashtra and 46 districts of Uttar Pradesh are affected.

Various state governments have managed to provide alternative drinking water to many of the affected districts over the years. Yet, according to the online Integrated Management Information System (IMIS) of the ministry of drinking water and sanitation, as on April 26, 3.28 crore people continue to drink contaminated water.

In one sense, fast depleting groundwater could also be the reason for such high contamination, according to experts. “About three to four decades ago, geologists had prescribed that no borewell must be sunk more than 30 metres deep. It wasn’t without logic, it was based on several studies that indicated that anything below 30 metres will have residues of chemicals or metals,” geologist Devaraja Reddy says.

In various parts of the country today, borewells have been sunk to 1,000ft and below, and geologists say there is no escaping contamination if this continues.

Separate data from the ministry of health and family welfare between 2010 and 2015 revealed that more than 16,528 people died due to diseases caused by water contamination across the country. The figures, officials said, are for five broad diseases caused by contaminated water. Specific information about how many deaths are caused by fluoride or arsenic is difficult to collate.

Fluoride is to be blamed for a majority of this contamination but arsenic is not too far behind, while salinity, nitrate and iron content also cause contamination (see table). Experts point out that intake of arsenic contaminated water, that is water with more than 0.05 mg/litre of arsenic, leads to various clinical complications which could result in death.

“This means that how many people actually die because of arsenic is difficult to assess, although arsenic could have caused a lot of ailments that lead to death,” a doctor said. According to World Health Organization (WHO), “Long-term exposure to arsenic can cause cancer and skin lesions. It has also been associated with developmental effects, cardiovascular disease, neurotoxicity and diabetes.”

Speaking about how fluoride affects the quality of life, Dr SR Lakshmipathi from state-run KC General Hospital said: “The way people live changes. Not only does fluoride affect joints and cause several related issues, but it begins to affect recovery. Fractures can take months together to heal and one becomes more prone to arthritis.”

Doctors also say that long-term exposure to fluoride not only causes skeletal fluorosis — more than a million people are affected by it — but it causes even non-skeletal fluorosis which lead to abortions and other problems.