What's in our water? Report warns of growing 'invisible' crisis of pollution

The planet is facing a mounting and “invisible” water pollution crisis, according to a hard-hitting World Bank report, which claims the issue is responsible for a one-third reduction in potential economic growth in the most heavily affected areas.

The study, which assembled the world’s largest database of water pollution, assesses how a combination of bacteria, sewage, chemicals and plastics suck oxygen from water supplies and transform water into poison for people and ecosystems.

While much international attention has been focused on the question of water quantity, not least as the planet warms, a secondary impact of the climate emergency has been its effect on water quality.

Because of the huge number of different pollutants entering the environment, researchers focused on the key measures for water quality laid down in the UN’s sustainable development goals, in particular nutrient loads, salt balances, and the overall environmental health.

The authors of the report employed a variety of technologies to study the problem, including satellite imaging of major algae blooms and artificial intelligence to assess the data they were collecting.

In particular researchers looked at a key measure called biological oxygen demand (BOD) to assess how much organic pollution is in water, using it as an indicator of overall water quality.

The researchers noted that when BOD crosses a certain threshold, GDP growth in areas affected by the problem drops by as much as a third because of the impact on health, agriculture and ecosystems.

Although issues with water pollution affect both rich and poor countries, the researchers suggest that developing countries have the least resources to deal with the issue.

A key contributor to poor water quality is nitrogen, which, applied as fertiliser in agriculture, eventually enters rivers, lakes and oceans where it transforms into nitrates.

Early exposure of children to nitrates affects their growth and brain development, impacting their health and adult earning potential.

The run-off and release into water from every additional kilogram of nitrogen fertiliser per hectare can increase the level of childhood stunting by as much as 19% percent and reduce future adult earnings by as much as 2%, compared with those who are not exposed.

Researchers also looked at the growing issue of salinity – salt contamination – blamed on more intense droughts, storm surges and rising water extraction. They estimated that at current levels its impact on agriculture means that the food lost because of saline water across the world would feed 170 million people.

The report notes that even wealthy countries still have serious issues with water pollution.

“Even high-income economies with well-resourced institutions find themselves unable to cope with the challenges,” the authors report, citing the notorious contamination of the drinking water supply in Flint in the US.

“Four decades after the passing of the Clean Water Act and the Safe Drinking Water Act, over 100,000 residents in Flint were exposed to lead in their drinking water.

“It required a national movement and three years for water to return to acceptable safety levels, but not before potentially thousands of children had been exposed to the irreversible harm caused by lead poisoning,” said the report.

“In Europe, countries such as France, Germany and Greece have been fined by the European Court of Justice for violating the regulatory limits for nitrates. Almost a third of monitoring stations in Germany present levels of nitrates exceeding the European Union’s limits.”

Related: ‘Nothing to worry about. The water is fine’: how Flint poisoned its people

“When it comes to what’s the cause of this problem, there are two forces,” Richard Damania, a World Bank senior economic advisor and a lead author of the report, told the Guardian.

“The first is climate change, which affects both water quantity and quality. The second is population growth and production. The debate has always focused on the issue of quantity, but it becomes obvious when you look below the surface that there are thousands of pollutants.

“We find that water pollution is a problem that affects both rich and poor countries, however the cocktail of chemicals changes as countries develop. In poor countries it is faecal bacteria and as GDP increases then nitrogen [from fertilisers] becomes the issue.”

“Clean water is a key factor for economic growth,” added the World Bank Group president, David Malpass.

“Deteriorating water quality is stalling economic growth, worsening health conditions, reducing food production, and exacerbating poverty in many countries.

“Their governments must take urgent actions to help tackle water pollution so that countries can grow faster in equitable and environmentally sustainable
ways.”