Toxic chemicals are endangering world’s most valuable supplies of groundwater

The first global survey of groundwater pollution has found that a toxic brew of pesticides, nitrogen fertilisers, industrial chemicals, and heavy metals is fouling groundwater everywhere, and that the damage is often worst in the very places where people most need water.

The report, Deep Trouble: The Hidden Threat of Groundwater Pollution, published by the environmental research organisation, the Worldwatch Institute, based in Washington, found that groundwater contamination is already widespread, from high levels of pesticides in wells in California’s San Joaquin Valley to excessive nitrates in groundwater in four northern Chinese provinces.

“Groundwater contamination is an irreversible act that will deprive future generations of one of life’s basic resources,” said Payal Sampat, author of the report. “In the next 50 years, an additional three billion people are expected to inhabit the Earth, creating even more demand for water for drinking, irrigation, and industry. But we’re polluting our cheapest and most easily accessible supply of water. Most groundwater is still pristine, but unless we take immediate action, clean groundwater will not be there when we need it.”

According to Sampat, 97% of the planet’s liquid freshwater is stored in underground aquifers, with nearly one third of the human population –from both rich and poor nations – depending almost exclusively on groundwater for drinking. Almost 99% of the rural population in the United States depend on groundwater, as do 80% of India’s villagers. “One of the most disturbing aspects of the problem is that groundwater pollution is essentially permanent,” said Sampat, explaining that water moves too slowly underground to flush out or dilute toxic chemicals. Water that enters an aquifer remains there for an average of 1,400 years, compared to only 16 days for rivers, leading to situations such as Londoners drinking water that possibly fell as rain as long ago as the last Ice Age, says Sampat.

Sampat calls for a systematic overhaul of industrial agriculture, siting examples of how farmers and factories are preventing groundwater pollution. Since 1998, farmers in China’s Yunnan Province have eliminated their use of fungicides, whilst doubling rice yields, by planting a wide variety of grain. At the same time, several water utilities in Germany now pay farmers to switch to organic operations as this option is more cost-effective than removing chemicals from water supplies.

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