Home / Articles / How to Find the Source of a Water Leak

How to Find the Source of a Water Leak

By Central Coast Building Diagnostics · August 3, 2026

Start with where the water shows up — not where you think it started

The location of a stain or wet spot is rarely the location of the actual entry point. Water travels along framing, sheathing, and finish materials before it becomes visible, sometimes moving several feet from where it entered.

Rule out the obvious first

Plumbing lines, HVAC condensate, and appliance connections near the affected area should be checked early — they’re often easier to confirm or rule out than an exterior source.

Look at the building as a system

Roofing, flashing, windows, cladding, and drainage all interact. A leak that seems tied to a window may actually originate at a roof-to-wall intersection above it.

When to bring in an investigation

If the source isn’t obvious after a reasonable look, or a repair has already failed once, a systematic investigation — using moisture mapping and, where useful, infrared thermography — is usually faster and cheaper than repeated guesswork.

---