A long time ago, there was a long and big river in Mainland China called the Yellow River. It was good for irrigating farms but it often made serious mischief in China. So the emperor assigned Ta-Yu to resolve those problems. Very well, I won't go home." During many years, he was concentrating on his hard work, and then he returned home. He had three chances to go home looking for his wife and children, but he didn't. finally, he succeeded and the Yellow River didn't make problems any more. The people who lived on the banks of the Yellow River respected him and chose him as a king.
Now, people call Ta-Yu the Water God because he is a good engineer for water-works. so this is the origin of the Water God.