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Aqua Flow Plumbing
Leak DetectionJune 24, 2026 · 4 min read

5 Signs of a Hidden Water Leak in Your San Jose Home

By the time you can see the damage from a hidden leak, water has often been running for weeks. These are the five signs we tell every San Jose homeowner to watch for.

First, a water bill that climbs without explanation. San Jose Water bills show your usage in units; if yours jumps and nothing about your routine changed, suspect a leak. Second, the sound of running water when everything is off. Stand in a quiet hallway at night: a faint hiss near a wall or floor is worth investigating.

Third, warm spots on the floor. Many South Bay homes are built on slabs with hot water lines running through them; a warm patch on tile or hardwood often means a hot-side slab leak. Fourth, musty smells or mildew in a room that should be dry, because moisture trapped in walls feeds mold long before stains appear. Fifth, low water pressure at fixtures that used to run strong.

There is a two-minute test you can do today. Turn off every fixture and appliance that uses water, then look at your water meter. Most meters have a small leak-detection dial (often a triangle or star). If it is moving with everything off, water is escaping somewhere.

If you spot any of these signs, call us before opening any walls. Professional leak detection pinpoints the source with minimal drywall surgery. That costs far less than exploratory demolition, and far less than repairing the water damage later. Slab-on-grade neighborhoods like Almaden Valley should be especially alert to warm-floor spots.

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