Long Riddles and Answers

Question: I'm the son of water, but when I return to water, I die. Who am I?

Question: If the day before yesterday was the 12th, then what is the day after tomorrow?

Question: You use me. I keep you neat. Every once in a while you empty me out. What am i?

Question: It makes everyone blind. You can't see it and it will always come back for you.

Question: When i was 4 my sister was half my age. Now I am 100. How old is my sister now?