Chicago Water Pressure Calculator

Calculate water pressure at a given location in Chicago's water distribution system based on elevation, floor level, and system supply pressure.

Water Main Supply Pressure (psi) Typical Chicago street-level main pressure: 60–100 psi

Street Elevation at Your Location (ft above sea level) Chicago elevations range ~578–672 ft. Average street level ≈ 595 ft

Floor Number Ground floor = 1. Each floor adds ~10 ft of elevation.

Floor-to-Floor Height (ft) Residential: ~9–10 ft; Commercial: ~12–14 ft

Estimated Pipe Friction Loss (psi) Typical residential service line loss: 2–10 psi

P_fixture = P_supply − (h / 2.31) − P_friction

P_fixture – Residual water pressure at the fixture (psi)
P_supply – Chicago water main supply pressure at street level (psi)
h – Vertical height of fixture above street level (ft) = (floor − 1) × floor-to-floor height
2.31 – Conversion factor: 1 psi = 2.31 ft of water column (derived from water density 62.4 lb/ft³)
P_friction – Pressure loss due to pipe friction in the service line (psi)

Example: 80 psi supply, 5th floor (40 ft above street), 5 psi friction loss:
P = 80 − (40 / 2.31) − 5 = 80 − 17.32 − 5 = 57.68 psi

Chicago Department of Water Management maintains street-level main pressures of 60–100 psi across the distribution system.
Water density assumed at 62.4 lb/ft³ (fresh water at ~60°F), giving the 2.31 ft/psi conversion.
Each floor is modeled as adding floor-to-floor height feet of elevation; ground floor (Floor 1) is at street level.
Pipe friction loss is a simplified lumped estimate. Actual loss depends on pipe diameter, length, material, and flow rate (Hazen-Williams or Darcy-Weisbach equations).
Chicago Plumbing Code (Title 18-29-604.8): Minimum water pressure at any fixture shall not be less than 20 psi.
Chicago Plumbing Code: Where pressure exceeds 80 psi, a pressure-reducing valve (PRV) is recommended to protect the system.
Chicago street elevations range from ~578 ft (lakefront) to ~672 ft (northwest neighborhoods) above mean sea level (NAVD 88).
This calculator does not account for dynamic (flowing) pressure losses in building risers, water meters, or backflow preventers, which can add 5–15 psi additional loss.
For high-rise buildings (>6 stories), Chicago code requires engineered booster pump systems; consult a licensed plumbing engineer.

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