I think that I saw a thread here a couple of years back where the Government announced that Taipei Water was fit to drink without the need to boil or filter.
Then again, in many countries the old habits stay there “we always boil it”, so why change.
Mind you, as a kid in Australia, in regional areas, drinking water came from a Rainwater Tank out back, and that water of course came from the roof. We didnt die or even get stomach problems. Mind you, we had to replace one tank as it had developed a leak, and when we started to dismantle it we found that the bottom inch or so was just sludge - no doubt why the outlet pipe was a couple of inches up the side. Of course god knows what was in the roof gutters and coating the roof. Non drinking water came from the town water pipes, was not filtered - so we had 3 taps in the kitchen, hot, cold and drinking.