Keep in mind, any leaks in the water heater will run down and out the bottom of the tank, usually running out through one of the support leg holes. The most common place to check for water leaks are the threads on the drain valve.

The manufactures don’t use any thread sealant in most cases (pipe dope is the best solution for a sealant), also inspect threads around the temperature control, relief valve, anode, and inlet and outlet fittings.

Inspect the inside of the relief valve for seepage as well. An indicator of a leak will be black or green residue inside were the relief tube screws in.

If you suspect a leak in a weld or seam in the main part of the water heater, run you hand around the outside skin of the tank. If you find one spot a lot hotter then there is a possibility of a leak in that area. The hot water gets trapped in the insulation making a noticeable temperature difference to the touch.