How much psi is required to lift wastewater at a lift station 42 ft?

How much psi is required to lift wastewater at a lift station 42 ft?

• A. 21 psi
• B. 48 psi
• C. 97 psi
• D. 18 psi

Answer: (D)

Raising wastewater by a vertical lift uses hydrostatic head—pressure from a column of water. Each foot of water depth adds about 0.433 psi of pressure. So for 42 feet, the needed pressure is 42 × 0.433 ≈ 18.2 psi. That’s why 18 psi is the right answer. The other numbers would correspond to much taller lifts (roughly 48 ft for 21 psi, 111 ft for 48 psi, and about 224 ft for 97 psi), which doesn’t match a 42 ft lift.

Raising wastewater by a vertical lift uses hydrostatic head—pressure from a column of water. Each foot of water depth adds about 0.433 psi of pressure. So for 42 feet, the needed pressure is 42 × 0.433 ≈ 18.2 psi. That’s why 18 psi is the right answer. The other numbers would correspond to much taller lifts (roughly 48 ft for 21 psi, 111 ft for 48 psi, and about 224 ft for 97 psi), which doesn’t match a 42 ft lift.