heh.. first step is to rewire that water heater.. NEVER put something critical like a fridge on the same circuit as a water heater or anything- even if it's a gas heater and only uses the electrics for control circuitry. oh well.. I didn't design the house..
(TX has some stupid ass electric codes anyway.. WTF made it code that you have to put the breaker box on the OUTSIDE of the house?!

every time my air compressor or chop saw comes on and it's cold outside, it blows the breakers. I'd sure hate for my wife to click on the hair dryer on a cold day and have to walk halfway around the back of the house to get to the box and reset it. idiots.
ummm, anyway.. sounds like the controls on your water heater are going out.. if it keeps blowing the reset button like that, it's got a problem that needs addressed, or the tank needs replaced. generally expect 10-15 years out of a water heater. if this one is less than 10 yrs old, look deeper.. if it's more than 12 or so, just replace it and be done. you're basically doing yourself a favor in the long run since you're doing it before the tanks rusts through and dumps 40 gallons of hot water in your utility room.
grrrrrr