"Seventy to ninety percent of China's water table is polluted. Polluted water table, polluted food."
The quote is from Gregory Copley's March 20 discussion on the John Batchelor radio show about President Xi Jinping's planned visit with President Donald Trump, to occur perhaps as early as April.
Gregory's overview of China's food security crisis is from the 7:11 to 10:09 minute mark on the podcast for the segment.
As to what Xi is doing about the crisis, as much as possible, which isn't saying much. Cleaning up a water table for a single small region is a very lengthy and expensive process; doing the same for a nation is an almost unthinkable undertaking. There will have to be leaps in technology to pull it off; China will need to become a large importer of food in the meantime.
For a graphic introduction to China's water pollution crisis, which hasn't gotten nearly as much attention in the international press as the air pollution, see: China admits pollution brought about 'cancer villages'; RT, February 2013.
See also As Groundwater Dwindles, a Global Food Shock Looms; National Geographic, December 22, 2016