[bpodgursky]

Yeah E. coli is the one thing that can change seasonally, that's fair. Still testable or filterable if you want to get a cheap purifier.

(also personally the contaminant I'm least fussed about)

[hanniabu]

Usually the notices are for lead. Other times they don't specify and just say don't use it so I can only assume it's something worse if they don't want to mention why.