Replace the anode rod of the water heater to fix the swampy smell and black water.
Items Needed
3/4“ plug
Flexible aluminum anode rod
1 1/16-inch deep socket
Instructions
Remove the old anode rod by closing the water supply, draining off several gallons, then unscrew the old rod with the socket, ratchet, and a breaker bar. You might have to have another person bear hug the water heater.
Attach plumbers tape to the new rod and insert it into the hole. Be careful not to cross-thread. Hand tighten only.