As further a cautionary note, it should be added, since the OP asked if he can bypass it, (I assume he's talking about the pressure/temp relief valve) that modifying or eliminating the valve will effective turn your water heater into a bomb if the temp controls malfunction. Anything that heats or boils water NEEDS to have a relief valve. The destructive power of hot water/steam under pressure can be devastating. It's recommended that the valve be actuated several times every year to make sure it's still in working order.