Not Bugs, but Features[no description provided]
“[Mukhande Singh] said “real water” should expire after a few months. His does. “It stays most fresh within one lunar cycle of delivery,” he said. “If it sits around too long, it’ll turn green. People don’t even realize that because all their water’s dead, so they never see it turn green.”
(Unfiltered Fervor: The Rush to Get Off the Water Grid, Nellie Bowles, NYTimes, Dec 29, 2017.)
So those things turning the water green? Apparently, not bugs, but features. In unrelated "not understanding food science" news, don't buy the Mellow sous vide machine. Features.