If street pressure is 40 psi and 12 psi is lost to friction, the remaining pressure can be expressed as feet of head. What is the head in feet of water from the remaining pressure (28 psi)?

• A. 64.68 Feet of Head
• B. 28 Feet of Head
• C. 121.52 Feet of Head
• D. 42 Feet of Head

Answer: (A)

The concept being tested is converting pressure to an equivalent height of a water column. For water, 1 psi is about 2.31 feet of head. This comes from the relationship h = P/γ, using water’s weight density (γ ≈ 62.4 lb/ft³) and converting psi to pounds per square foot.

With 28 psi remaining, the head is 28 × 2.31 ≈ 64.68 feet of water. So the remaining pressure corresponds to roughly 64.7 feet of head.

This matches the idea that higher pressure translates to a taller column of water: 28 psi pushes about a 64.7 ft high water column.