The relief valve needs more then just tape,, you need to go to the hardware store and get some pipe dope.. put the Teflon tape on first then use the pipe dope over the tape,, this should stop that leak,, if it doesn't then the tank is cracked where the threads are,,,the valve coming into the house should have a packing nut around the stem,, use a wrench,, (adjustable or the right size wench) and tighten the nut clockwise a few turns,,, do not overtighten,,, just enough to stop the leak.. the two are not related,,, good luck,,