Apparently foodbourne intoxication is a food thing, not a water [tank] thing [1]. It seems heat-stable toxins are very rare in drinking water, as it isn't nutrient-rich enough to create enough toxins to affect you. Even biofilms don't really generate much toxins, they just leech off the microbes which cause issues.
Another example of this would be old rooftop water tanks in places like NYC. It's a giant tank which never gets cleaned, and often has all kinds of gross things in it, but (usually) no food for germs to munch on.
Another example of this would be old rooftop water tanks in places like NYC. It's a giant tank which never gets cleaned, and often has all kinds of gross things in it, but (usually) no food for germs to munch on.
[1] https://pubmed.ncbi.nlm.nih.gov/12385500/