The Dirtiest Pools in the World are in China

The crowded public pools in China are considered the dirtiest. A study of more than 5,600 swimming pools in 24 provinces found out that:

• Ten percent of them have high levels of urea (therefore, urine),
• the total percentage of bacteria in the swimming pool can reach 92.3 percent and E. Coli can reach 96.9 %

In 2008, a man died and more than 3,000 fell sick after ingesting fecal matter-laced pool water from the Mao Mao Municipal Pool in Beijing. 

sources: 1, 2