I was called to do a One Year Inspection prior to the expiration of the builder's warranty.  I do a lot of them.

Looking at this deck and door from the rear yard everything seemed normal enough.

Until I got closer.

You might not notice it from this photo.

I'm talking about what you see in the photo below.

That's it, right there.  Water.

Now, it had not rained in the past month.  There is a bedroom window above this door, but it could not have been opened during a recent rain storm.  There is no plumbing in the wall, service or drain.  There is a typical soffit overhang with a gutter, but all that was dry.

Coming inside, the floor around the door was dry according to my moisture meter.  I had my IR camera with me and looked at the wall above and around the door inside and out.   Nothing visible.  Similarly, inside, nothing thermal was visible in the floor or ceiling above.

Neither upstairs bathroom is anywhere nearby.  The closest, the Jack and Jill bath, is 20 feet above and to the left of this photo.  I had not tested the bathroom yet, it was dry, and this water is fresh, the puddle even growing slightly during the inspection.  The plumbing penetration to vent the kitchen and that bathroom is 30 feet or so to the left of this photo. He had not used the hose or watered the lawn that day.

I have to admit, I was stumped.

I NEVER DID FIGURE IT OUT!

My client had never noticed this puddle before.  I advised him to call me if it continued or grew.  He never did.

Sometimes things remain a mystery.  Any ideas as to this water's source?

My recommendation:  when you notice something out of the ordinary, and you cannot figure out a reason, watch it to see if it changes.  Maybe then you will find a change that leads you to the cause.  And then maybe you won't...