2 year old hot water heater draining itself at pressure valve

Hi,
To prevent leaking follow this

Place bucket under overflow pipe. Open and flush T&P valve clear of debris. If leak remains from valve, replace valve.
Reduce thermostat setting to prevent tank overheating and opening T&P relief valve.
Inspect bottom of tank by looking through combustion chamber. If water marks or heavy rusting is noticed or if water is noticed setting in combustion chamber bottom, then the water heater needs to be replaced.

Have you had a sprinkler system or a backflow preventer installed lately? If you you need to install a expansion tank installed on the cold water feed. T and P valve leakage can also be caused by over heating or mineral buildup getting in the seat , Like nnila suggests, pop the valve and flush it out. If all else fails, shut the power and water off to the tank and replace the T & P valve. Good luck, Tom