The area around the Yangtze River estuary is often referred to as "China's Venice", because of the large number of villages that straddle rivers in this part of East China. Fei Xiaoliu, 56, grew up next to the river in Changshu, a small city in Jiangsu province, washed by the Yangtze River.

It only takes about 20 seconds to walk from her house to the riverside. In the 1970s, the residents of rural Changshu carried their "portable toilets" - small wooden buckets - to the river bank, where a boat stopped every morning.

"We poured the waste into a container on the boat, which went from one village to another. The 'night soil' was applied to the fields as fertilizer," she said.