That's the question that you posed, yes. But other posters were asking about where did all the water come from.
Underwater reservoirs were most likely a factor, yes, but again, that was not the only source for the water. We see Texas rains--they can flood a place pretty fast. Multiply that by a hundred and you've got Noah's flood.
And yes. I say what I believe. I don't just parrot different sources because it 'sounds good'. If I was doing that, I wouldn't find it worth it to discuss this! :) "I say what I mean, and I mean what I say"...