CSLB C-36 Plumbing ContractorService, Repair, and MaintenanceEasy
A commercial building owner reports a sudden drop in water pressure throughout the entire building. The municipal water supply confirms no issues on their end. What is the most likely cause of this widespread pressure loss?
- AA burst pipe within a specific tenant's unit.
- BA localized clog in a single fixture's aerator.
- CA partially closed main shut-off valve or gate valve.
- DSediment buildup in individual water heater lines.
Show answer & explanationAnswer & explanation
Correct answer: C. A partially closed main shut-off valve or gate valve.
A sudden, widespread drop in water pressure throughout an entire building, with no municipal issues, strongly suggests a restriction at the primary entry point of water into the building. A partially closed main shut-off valve or a failing gate valve that is not fully open would restrict the overall water flow, causing a pressure drop everywhere.
Why the other options are wrong
- A. A burst pipe would cause a pressure drop, but typically also significant water damage and a continuous leak, and might not immediately affect *all* fixtures equally in terms of pressure drop without being noticed.
- B. A clogged aerator would only affect that specific faucet, not the entire building.
- D. Sediment in individual water heater lines would only affect hot water pressure in fixtures served by that heater, not the cold water or the entire building's pressure.
Widespread Water Pressure Loss
A noticeable decrease in water pressure across multiple fixtures or an entire building.
- Often indicates an issue with the main water supply to the building.
- Common causes include partially closed main valves or pressure regulator failures.
- Distinguished from localized pressure issues affecting single fixtures.
Memory trick: Pressure's low, check where the main flow did go.