Residents often faced a bitter choice: drink dirty, discolored water and risk sickness, or pay high prices for bottled water and risk poverty.

But artist-turned-environmentalist Huo Yalun has been on a mission to change that, installing filters to purify groundwater in the area in a bid to offer a safe alternative for ordinary people.

“We have seen many people in villages get cancer and skin diseases because of drinking the polluted water. But I wanted to … actually find a solution to the villagers’ drinking water problems,” he told AFP.

It has been a monumental task.

Decades of rapid development has left the world’s third longest river and its tributaries choked with toxic chemicals, plastic and garbage, threatening the main drinking water source of nearly 400 million people — a third of China’s population.