Question:
I would like to know how to calculate the water pressure
for gravity fed water supply systems. I am doing a 4-H club project on
supplying water to livestock from a water storage tank.

What is the formula for calculating the output pressure of a tank given
the factors of tank size and elevation and the size of the output pipe?

Replies:
It's really easy. If the vertical distance between the spigot and the
surface of the water is H inches, and you want the pressure in pounds
per square inch, you just calculate the weight in pounds of a column of
water one inch square by H inches high. The size of the output pipe
does matter a little, because causes a pressure drop, but at the water
speeds you're interested in the effect is small unless the pipe is very
narrow or very long. A garden hose, for example, doesn't produce much
of a pressure drop at household water pressures.

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