My moms 2006 Lucene only when it rains is wet on the passenger rear floor only. It only happens when it rains...it'* only on the rear passenger floor...... we have used a hose to run heavy water over the windows and doors etc. while someone is sitting in the rear seat and there is no leaking anywhere...... Where is this water coming from?

Check the trunk seals also.

Does it have a sunroof? If so, have you checked that the drain isn't clogged?

No sun roof..... no wetness anywhere else but floor of passenger side of back seat.

Likely a door seal then.

Does it park on any kind of slope or is it mostly on fairly-level ground?

Ah, found the problem..... pulled the carpet and seats.... ran water over windshield it leaking in the lower right corner of front seat, it was running back to the back seat floor.

Glad you found the source! Are you going to use windshield urethane to try to seal it? or have the shop re & re it?

Since it'* my 79 year old mother'*, I'm going to take it to a shop...I want it done completely so we don't have to worry about it again.

https://photos.app.goo.gl/hz4KDvHuyz5BEzSCA I found issue with water coming in a hole that a wire hanger was to fo in..... Seal it with aluminium tape and let a zip tie hold wires.....dried out carpet and will put it back in.

Not the windshield....... it is leaking out of the the factory holes that the wire holders and the trim panel retainers go into.... when you seal one hole, it just starts to come out of another hole higher up after a few seconds..... I cannot seem to find a drain location for this area..... it'* the same area that the wiring for the passenger door goes thru...... I'm stumped..... https://photos.app.goo.gl/hz4KDvHuyz5BEzSCA