Most water heater manufacturers recommend periodically draining a few gallons of water from the bottom of the water heater to remove loose sediment. For this purpose, they install a valve with a threaded hose connection at the base of the water heater. Attach a garden hose and carefully drain several gallons to your basement floor drain or sump pump. Be careful, and follow the manufacturer’s instructions – the water will be hot.
But here’s the catch: often the drain valve will leak after you close it. This may be because the valve is cheap, because it’s rarely used, or because the sediment you are draining sticks in the valve.
A plumber would replace the original cheap valve with a high-quality brass valve. What should you do? Cap the valve with a cheap ($1 or less) hose end cap. You can buy one at any hardware store. The rubber gasket in the cap will seal tightly against the end of the valve. The next time you want to drain water, just remove the cap and open the valve. Re-use the cap when you are done draining water.