How is water getting into my car?

RE: 1999 BMW 528i I have to park my car on the street in front of my house. For about 5 months now, whenever it rains a lot (which it does often in New Orleans) the carpet on the passenger side of my car is soaked through. There is no water anywhere else. Nothing else is even damp. But lots of water on the carpet/floor. How is it getting in? Can it be fixed? Is it an expensive fix??

First thing to check if you have a sun roof, is the drain tubes running from the sun roof through the interior sheet metal and out to see if they are plugged. There should also be a drain tube underneath for the air conditioning pan. Probably just take it somewhere so they can put it up on a lift and clean out all the drain tubes.

If it isn’t the sunroof, it might be the fresh air feed for the cabin air ventilation system. My Buick has an upward facing air vent in the engine compartment at the base of the windshield. There is a gasket that fits on the bottom of the windshield to divert water to either side of this vent. If the gasket is loose or falls off, then water can enter the vent. It fills the vent blower motor an then spills onto the carpet. I don’t know if your BMW has a similar system, but you might want to check into it if it isn’t the sunroof.

If the vents are ruled out I would take it to a glass company and have them check the windshield seal with compressed air. Maybe you should also venture out when it is pouring and sit in the car with some paper towels to see if you can tell where it’s getting in or run a garden hose on it. Is the headliner wet or water stained?

look for seals around the cabin filter if equipped