The fifth glass is RO filtered water taken from the tap (not filtered by PUR/Whirlpool filter) and frozen, then melted (contains flakes)
The RO filters are less than 3 months old. They are WATTS brand. The PUR/Whirlpool filter is about 2 weeks old. I have a glass if unfiltered tap water freezing and will attach a pic of it when it thaws out to see if it has flakes. So if anyone can give me some suggestions as what is causing the flakes I would appreciate it. We drink out of dark glass or dark Nalgene or stainless sports containers. So we have not noticed it before. I hate to think we have been drinking this crap all along. The only thing making me feel slightly better is that the flakes settle out pretty quick and being the courteous guy I am, I always let my wife get the last drink.