A tank placed in certain height will supply a certain pounds pressure per square inch. For example, a tank placed in the 25-inch tower will at least give a 12.5 lbs of pressure per square inch. The below section of this page provides you the water pressure formula for height which allows you to calculate the pressure based on height above the outlet. According to the formula, pressure can be determined by multiplying the height above the outlet value with 9.81.
The above water pressure height formula in this page will be a very useful and efficient one for the civil engineers to calculate the water pressure at heights. Also, you can refer to the calculator link above to know the resultant value easily.