Step 2 · Drain the Tank Partially
To access the T&P valve without a major flood, you must lower the water level inside the tank. Connect a standard garden hose to the drain valve spigot located near the bottom of the water heater. Route the other end of the hose to a floor drain, utility sink, or outside. To prevent a vacuum from forming and to speed up the draining process, open a hot water faucet in a nearby sink or tub. Now, open the drain valve on the water heater. Since the T&P valve is on the side, you only need to drain a few gallons until the water level is below the valve's location.