Until two days ago when he ran out of water completely. Since he had only been taking sips of water and not really drinking to his body's satisfaction, he was dehydrated before the day ended.
When he realized that he would not be able to survive, he had sat on his favorite chair and decided to leave this world on it.
Some people would get confused as to why he would get dehydrated when it was raining heavily. Why didn't he just drink the rain water?
He had thought of this as a solution before, but seeing as how people had turned into zombies without warning, he couldn't be careless. Thus, he took some rain water and fed it to his only companion in that building, a rat.
He didn't even know where the rat had come from. It appeared there one day when the water started to flood the building. He assumed that its home had been flooded as well, which was why it moved there.
