As of 2002, Thailand had less water available per person than any other country in Asia, and nearly one-third of its water was "unsuitable for human consumption."[67] Non-potable water was a result of increasing untreated domestic sewage, industrial waste water, and solid hazardous wastes.[67] This is a critical environmental problem for Thailand.[1] Like air pollution, water pollution is most serious in the populous central region, with high levels of industrial and domestic waste water.