Storage tanks, elevation and natural (non-assisted pressure)

·         Water pressure at the outlet is determined by several factors

o    Located at the bottom of a tank

o    The temperature of the water

§  Which changes its specific gravity

o    The height of the water column

§  How high above the outlet (spigot) the water is exiting the tank

·         The general formula is:

o    Feet elevation divided by 2.31 equals PSI (Pounds per Square Inch)

o    Ft Elevation / 2.31 = XX PSI

§  Example

·         A storage tank 46.2 feet above the ground

o    The calculation - 46.2 / 2.31 = 20 psi

·         The amount of water in the reservoir has absolutely no affect on the pressure that it exerts

o    The only determining factors are:

§  Depth (Water Column or Height)

§  Water density (determined by altitude and temperature)

·         Example:

o    Fresh Water is based at 0.43 psi per foot of depth

o    Sea Water is based at 0.44 psi per foot of depth

§  The water pressure at a fresh water dam 100 feet deep is 43.3 psi

§  The pressure is the same whether the reservoir is 10 feet long or 25 miles long.

The beauty of an elevated water tank is that there is no mechanical aid needed to flow the water from the tank. You don't need electricity or other means to operate a pump to flow water.