Here are few of Pete's prior answer for some of your questions :

1) Water contamination due to chemical/oil/grease/organic sources.  We are on top of this one

2) Water desalination to address water needs by people, industry, agriculture, naval, etc.  We don’t, at this time, see a direct use for plasma in desalination. Reverse osmosis should be more energy efficient.  Although we do have proposals where we can enhance the efficiency of reverse osmosis.