CSLB C-36 Plumbing ContractorService, Repair, and MaintenanceHard
A commercial property manager reports that their water bill has significantly increased over the past two months, and they've noticed damp spots on a basement wall that are not associated with any visible leaks from exposed pipes. The building has a copper water supply system. What is the most likely cause of this hidden water loss?
- ACondensation buildup on cold water pipes.
- BCapillary action drawing moisture from foundation cracks.
- CAn underground slab leak in the main water supply line.
- DA malfunctioning pressure reducing valve (PRV).
Show answer & explanationAnswer & explanation
Correct answer: C. An underground slab leak in the main water supply line.
A significant increase in water bill combined with unexplained dampness, especially on a basement wall with no visible pipe leaks, strongly indicates a hidden underground slab leak in the main water supply line. Copper pipes are susceptible to pinhole leaks over time.
Why the other options are wrong
- A. Condensation buildup usually occurs on exposed pipes and wouldn't cause a significant increase in the water bill as it's atmospheric moisture, not system water loss.
- B. Capillary action from foundation cracks can cause dampness, but it wouldn't account for a 'significantly increased' water bill, as it's not a direct water loss from the supply system.
- D. A PRV malfunction typically leads to high pressure or low pressure, but not directly to a hidden leak and increased water bill without other symptoms.
Hidden Slab Leak Detection
Identifying water leaks occurring beneath a building's concrete slab or underground, often characterized by unexplained water bill increases and damp spots.
- Unexplained high water bill
- Warm/damp spots on floors or walls
- Sound of running water when no fixtures are on
- Cracks in slab or foundation
Memory trick: Hidden leak? High bill, damp wall, slab's call!