How do I determine how much water is in my water heater's tank?
If your water heater has a drain port that uses a conventional garden hose type fitting, consider to attach a short piece of hose to the port. It can also take a standard washing machine hose. Ensure that you have no pressure, as &quot;almost nonexistent&quot; is still some pressure.
Open the valve for the drain port while the end of the washing machine hose is at the height of the top of the water heater. There should be no water visible when the end is higher. As you lower the end of the hose, you will begin to see water approaching the opening. It will match the level of the water in the tank.
If there is pressure in the system, none of this will work, as the water pressure, even if low, will force water from the tank into the hose, regardless of the level of the hose end.