At what static pressure should a water-pressure reducing valve be installed in a building?

• A. When pressure exceeds 60 psi
• B. When pressure exceeds 80 psi
• C. When pressure exceeds 100 psi
• D. When pressure exceeds 120 psi

Answer: (B)

When water pressure is too high, it stresses pipes, fittings, and appliances and can cause leaks and water hammer. A water-pressure reducing valve (PRV) is used to bring that high incoming pressure down to a safer, more typical residential range (around 50–60 psi) so plumbing components last longer and operate more reliably. The guideline for installing a PRV is when the static pressure exceeds about 80 psi. At or above this level, the risk of damaging fixtures and triggering issues increases, so placing a regulator then protects the system and helps maintain a safer, more manageable pressure. If the pressure is only 60 psi, a PRV is often unnecessary because components are generally rated for that range; waiting until 100 or 120 psi would leave the system exposed to excessive pressure before action is taken, which is why 80 psi is the recommended trigger.