I have been using a Rubbermaid 23 gallon recycling can for my ATO and it still reads 0 TDS after 4+ years of use and it has never once been cleaned or emptied out. I also use a 30G Rubbermaid Roughneck trashcan for my water mixing and again it has never been a problem in 9 years of use.
I had a Brute as a mixing vat, ended up with phosphates and a blow out (and a crap ton of mixed water down the drain). Switched to a Roughneck, no problems. I think it's just the Brute line that had the issue, something about either the type of plastic they were using or the lubricant that they spray the molds with (which then impregnates the plastic).
Not sure, I would think so since they're structural foam. The Roughneck trashcans, if I remember, are NSF grade 2 food safe plastic, the Brutes are a different grade of plastic, which might be why they leech.