Everyone knows that you can drink the water in the toilet tank (NOT the bowl!)

But during a water shortage, if people have access to non-potable (contaminated) water, you know they'll be adding it to the toilet tank to flush the toilets because they're so used to just hitting the lever.

BUT... just how clean-able is the inside of the toilet tank? Sure, the outside is glazed ceramic, but the inside looks more porous. Many years ago, people were putting bricks in the toilet tanks to save water via displacement. The porous bricks became bacteria factories and started stinking.

So, if non-potable is added to the toilet tank, is the tank contaminated forever, never to be a source of drinkable water again? Does it matter as to contaminants (organic/inorganic)? If you bleached the tank, would it really take care of the organic contaminants? Would repeated use (flushing) water down inorganics to a safe level?

I don't remember ever seeing this issue addressed, ever, anywhere.

Sue