I myself only boil the water for some minutes. I don't know where those resistant bacteria live and how dangerous they can be, but I would think the chances that they are in my water won't be big, as I would only boil water for drinking that already looks reasonable safe to me. So I only use water from for example a cold clear moving (mountain)river, in stead of sewer water. It looks to me that the chances of finding those heat-resistant bacteria are much smaller in cold water than it hot, but I'm not totally sure about that.
When I find a very clear looking mountain river, with fresh cold water coming directly from the snow, I have drunk it without purification in the past without problems.
When in for example africa in some survival situation, where you haven't got the choice to drink water from a safe looking river, but only from a mudpool or something, I'm sure I would try to boil my water as long as possible too.