ASV notes on Genesis 7:11-12
How can we understand this; “All the fountains of the great deep burst open” It could be that in the centre of the earth there was a huge amount of water, called the great deep and God made it burst open for it to flood out, it says that it burst open, that could mean that the water that streamed out is no longer there.
And then we have; “The windows and floodgates of the heavens were opened” The water above those windows and floodgates could be in the heavens outside the universe, above the firmament and it seems that God opened those windows and gates for the water to flood down like heavy, heavy rain. Then after 40 days He closed them and it could be that in this “room” there is an infinite amount of water for use when needed.
ASV notes on Genesis 7:15-16
All the living went in two by two which there was the breath and spirit of life; there are spirits in animals and God can communicate with them, but they too can disobey God and be possessed by evil spirits. Seven pairs of clean animals went into the wooden box, and one pair of unclean and crawling things and God picked all of them and led them to the ark. In the ark there were no evil spirits. The spirit of life is in animals and it seems likely that we will have animals in heaven.
ASV notes on Genesis 7:24
When the flood started it rained for forty days until the water covered the earth completely, 23 feet above the highest mountain peak, and then the water stayed like that for 150 days before it started to decline.