Have you had you're windshield replaced ?
some installers dont like putting on glue on the bottom of windshield and it will cause
to leak true there !
I speak from from my own experience, I had to replaced my carpet on my 2002 Tacoma cause ot it !
Possibly the AC moisture removal system has a hose that runs inside the interior (my 94 Tercel had one) and when people got in the car, they would nudge it with their feet, and eventually it came loose and the water wicked from the outside or ambient air thru the system leaked on the passenger floor/carpet. I guess they would've rerouted that kind of faulty engineering by now, but might be worth a check. Look under the glovebox and near the kick panel, if you see about a 3/8" diameter black tube anywhere in that area, that might be where the leak is. Hopefully i'm way wrong and it's something simple!