How do I stop a waterheater drain from leaking?

There’s a very good chance that crud from the draining has jammed the valve mechanism, preventing it from closing completely. Happens all the time. You could replace the valve, but a cheaper fix (and that wouldn’t require draining the tank again) is to buy a hose cap that just plugs the valve until you’re ready to drain again. No more drip pan.

Sounds like a washer in the faucet has gone bad, or perhaps some debris from the draining process has clogged the valve. The hose cap sounds like a good idea.

You might want to check your hot water heater setting. The plumber told me if you have too hot of water, it weakens all of your faucets, and they will leak.

Note- If you go the hose cap route, you’ll want to put a hose washer in there too or the water will end up pushing out around the threads