Mine is twofold really, this reason and another, my original Zodiac sign (until they started messing with them) is/was Cancer, the sign of the Crab, now Cancer is one of the three Water signs and also certain variants of crabs are known to be around water, so this is Reason Number One.
The best version I can think of for Reason Number Two was when I was much younger, I was on an amateur, after school swim team and the coaches noticed that I loved the water.
"hydro" is the abbreviated name for hydropower, that is electricity generated from the movement of large amounts of water (usually a large and powerful river).
So (water = hydro + boy = lad) hence "hydrolad" (the water boy, NOT the football team variety).
So THIS is my rather convoluted explanation of my nickname or user name, so you can forget to call me by my "nickname", but
please don't forget to call me for Supper (and if you're the least bit curious, just ask me what's on a "Southern" table some nights!) [bIG Grin]