Most Portland leaks fall into a few patterns we see weekly. Pre-1940 inner SE and NE homes — Irvington, Ladd's Addition, Eastmoreland, inner SE — still run a lot of original galvanized supply piping. When galvanized leaks, it's usually a sign the pipe wall has thinned to the point where one pinhole means another is coming. Mid-century SW Portland homes built on slab can develop single-point slab leaks, almost always on hot supply lines (post-1970 era especially). Once a slab leak is located, it's a straightforward single-point repair — what we don't do is run sonic equipment to find one you can't see at all.
If your only signal is a spiking water bill with nothing visibly wet anywhere in the house, you want a specialized leak-detection company that runs acoustic, sonic, and thermal gear we don't carry. We'll point you to one we trust.
Portland's freeze-thaw window — usually one or two cold snaps a winter — is the other recurring driver. Pinhole leaks on poorly insulated runs in crawl spaces, basements, and exterior-facing walls show up most often in the weeks after a hard freeze.