What is the typical water pressure for an older standpipe system on the top floor of a building?

• A. 75 psi
• B. 100 psi
• C. 65 psi
• D. 30 psi

Answer: (C)

Water pressure on the top floor of an older standpipe is mainly about hydraulic head and what the piping can reliably deliver. As water climbs up the standpipe to higher floors, the pressure at the outlet drops due to elevation and friction losses along the pipe and hose. Designers of older systems typically aimed for about 65 psi at the top-floor outlets because that level gives a practical, usable fire stream with standard attack lines without overloading the pumps and smaller pipes used in those buildings. A pressure like 65 psi provides enough force to push water through a hose and produce a decent stream, while pressures much lower (around 30 psi) would struggle to deliver an adequate flow, and pressures much higher (around 75 or 100 psi) exceed what those older systems commonly supplied at the top floor.