How much pressure is in a water tank?

What kind of tank? How much water is in it? Is there air in the tank? What fills the tank? What kind of pressure from where and what?

answer

If the tank is gravity fed, multiply .431 times the altitude that the source is above the tank. For example, the reservoir supplying my domestic water system is approximately 200 feet higher than the valley floor I live on. My water pressure is slightly over 80 psi. If the tank is pump fed, and if you have no information on the pump, you will have to put a gauge on the system.

A household well water tank usually has 50 or 60 psi in the tank.