There are lots of ways to fool environmental inspectors. Here we take a look at how factories in China do it.
Playing dirty: how factories hide their pollution in China.
Water pollution is one of China's most critical environmental problems.
A staggering 70 percent of China's rivers and lakes are too polluted for human use.
More than half of this pollution comes from factories.
There are laws against pollution in China but they are poorly enforced and need to be strengthened.
Many companies - domestic and international alike - simply break them because it's cheaper to do so and at the end of the day they are looking to make the biggest profit they can.
In fact many companies go to great lengths to hide just how much pollution they are dumping into the environment.
Greenpeace China has discovered Ten Dirty Tricks that factories play in China to conceal just how much and how toxic their effluent is.
Here's what we found out (scroll down):