Science states that you can't survive more than 3 days without water
No it doesn't. You can go at least a week without water under normal circumstances. Under abnormal circumstances, such as being trapped under a huge pile of rocks and being hungry and motionless (and therefore using up very little energy to do things like walking, running, or eating), you can definitely survive a lot longer. Hence, fifteen days. It's very unlikely, but not impossible.
Comparing that to a man walking on water, raising the dead, turning water into wine, and then being killed, coming back, and going into the sky is absurd. 100% absurd, in fact.
Unlikely things happen all the time, but this is expected when there are 6.5 billion people for unlikely things to happen to. A "miracle" is just a notable deviation from standard.
The only reason you feel this way is because these events were actually witnessed and put through the media. In other words, if these events had never happened, and I told you that a girl could survive days buried in rubble, you'd call me crazy and mock me just as you are mocking Jesus being able to walk on water. But, we know that days after the Haiti earthquake, a young girl was reported to have been found alive after being buried in rubble for weeks. Science states that you can't survive more than 3 days without water, so a young girl doing it while being covered in rocks and debris for over 2 weeks is unheard of. The same way a man walking on water is unheard of.
http://news.bbc.co.uk/2/hi/8484317.stm