Revised Valuation, page-18

Hi all
this paragraph taken for the last post, ie grade 3 or lower safe for human use so i gather grade 4 is not to good. next atricle on Dianchi lake that is grade 4, could be putting the extra boats on xinyung to get this one finished quickly and then move on to Dianchi

China divides its water resources into six grades, with the top three considered safe for human use, and the lowest, “below grade V”, unfit even for industrial or irrigation purposes.

http://www.chinadaily.com.cn/global/2019-12/02/content_37526876.htm