When you are checking on or replacing your TP valve, make sure it's the output is directed in the right place to avoid any problems. According to Accurate Inspections
, "The pressure temperature relief valve output should always be directed outside the building and downwards, about 6 to 12 inches off the surface of the ground or flatwork concrete." If the water that gets released is not directed in the right place or the right direction, it could do damage to the water heater or anything that the output valve is pointed at. If the output valve is blocked, that basically negates the whole reason that your water heater has a relief valve in the first place! It seems that 6 to 12 inches off the surface is a good rule of thumb. I would err on the side of more distance, just to be on the safe side!