I have water inside the passenger door of my 2011 Nissan Altima. I can hear it sloshing whenever I make a turn, start, or stop. I’m concerned that this will rust out the door. How can I get it out of there?
Along the bottom of the door there should be 2 or 3 drain holes, designed to let any water in the door drain out. These drain holes can get plugged. Look at the bottom of the door and see if you can remove any blockage from the drains. Be prepared for a stream of water to run out.
If you think about it, every car door should have water in it. There’s no way the door window gasket can prevent 100% of the rain water from going down the inside of door. Some water pretty much has to get in. Think how difficult that would be to prevent when you are driving 60 mph in a rainstorm. So the car makers, they simply provide holes in the bottom of the door so what water gets in drains out. Like @asemaster says, the drain holes in your car door must be blocked. It’s a good idea to make this part of preventive maintenance. Whenever I change the oil in my cars, while the oil is draining out, I use some of that time to inspect and in necessary clean out the door drain holes.