They do not leak due to the water proof seal that is at the bottom of the door. Now water can still leak only though if people actively splash water frhom inside the tub.
The seals on your windows have a leak or in need of replacement.
figure out how the water is getting inside the wall, as it is coming in from outside and should not be allowed to continue as it will cause a lot more issues than a wet floor if not fixed.
One of three possibilities: A windshield or door leak allows rainwater or other outside water in. A leak in the heater core allows radiator coolant to leak inside the cabin. A plugged condensate drain line is causing AC condensate to drip to the inside. My door seal is bad and lets in rain water. Try to use the water hose and see if you can see the water leaking in. That's what we did. Had the same problem..Had to find the A/C drain hose by drilling a hole on pass. side wheel well..then re-routed hose to drain down instead of inside the vehicle.
A water leak from the radiator in to the passenger compartment is usually a sign of a leak in the heater core. If the water is not from the radiator then there may be a leak in a window or door seal, or a hole in the undercarriage that is allowing water from the road to soak the carpet..
It rusted out
You have to find the source of the leak. Is the door leaking somewhere, probably at the bottom? The area around the sunroof is also prone to leaking. If there is a lot of water on the floor, you should take out the mats and rugs before they get moldy. This will also make it easier to find the leak. One technique it to have someone sit inside and observe while you spray water from a hose on the car, around the door, around the sunroof, etc. Open the hood check where the battery goes look under the brake servo is a water drain clean it when is raining it fills with water and them goes inside.
there is a leak in the drain pan that the evaporator sits in inside your furnance
Bad window seal?
If the leak is by the passenger floor-- could be the heater core check to see if this leak is engine coolant or just water. Could be a leaking windshield seal could be a door seal could be evaporator line is plugged
Most leaks occur because of a failing rubber seal. Open your hatch and you'll see a rubber hose that outlines the inside of your hatch, if you follow it around the inside, you may find one that is failing. Find a water trail and track that to the seal and this should be the culprit. Go to your local hardware store and purchase stop leak or a rubber sealer and use liberally around the area.
Our bodies aren't 75% water, just about 12-15%. The water is part of a solution inside the cells. If a cell ruptures, that contents will leak somewhere.