The data shows that 81.8 percent of surface water was graded Class I to III (good quality) in the January-May period, up 1 percentage point from the same period last year, while the figure for Class V water fell 0.7 percentage points year on year to 2.1 percent.

 

Surface water quality in China is divided into five classes, with Class I being the best.

 

For major rivers, including the Yangtze River and the Yellow River, 83.5 percent of the water quality was graded Class I to III in the first five months, up 1.2 percentage points year on year, and 2 percent was graded Class V, down 0.8 percentage points year on year.