What is the typical pressure in psi in a water main 415 feet below an elevated tank?

To determine the typical pressure in psi in a water main located 415 feet below an elevated tank, we can use the concept of hydrostatic pressure, which is derived from the height of the water column. The pressure generated by a water column can be calculated using the formula:

Pressure (psi) = Height (feet) x 0.433

In this circumstance, we multiply the height of 415 feet by the conversion factor of 0.433 psi per foot.

Calculating this gives:

Pressure = 415 feet × 0.433 psi/foot ≈ 179.645 psi

Rounding this value gives a typical pressure of approximately 180 psi. This result aligns with the choice that indicates approximately 180 psi being the correct answer. This high pressure is typical for water systems, especially those involving elevated tanks, as it ensures adequate flow and pressure for distribution throughout the water network, accommodating fluctuations in demand and elevation across the system.

The other options represent pressures that are inconsistent with the hydrostatic calculations for that particular height.