Where is the water leaking under the cabin?
4 Answers
After ruling out human factors, if water is still dripping under the car cabin, you should check the car's drainage outlets. Here is the relevant information: Rainwater entering through unclosed windows: After parking, if the owner fails to ensure the windows are tightly closed, rainwater can seep into various parts of the car through the unclosed windows. Over time, water will accumulate under the cabin. Issues with drainage outlets: After eliminating human factors, if water is still present under the cabin, inspect the car's drainage outlets. There are four drainage outlets in total—the front two are for sunroof drainage, and the rear two are for draining water flowing on the car.
There is water under the cabin, and I have encountered this issue several times. The most common cause is a clogged condensate drain pipe from the air conditioning. When you turn on the AC in summer, it's normal for water to drain from there, but if dust or leaves block the pipe, the water can backflow into the car. Another possibility is a leaking heater core, especially in winter—if antifreeze leaks out, it will wet the floor and has a slightly sweet smell, which requires attention. Aging door seals could also be the culprit, allowing rainwater to seep through the gaps, particularly in older cars where the rubber has hardened. If the sunroof drain is clogged, rainwater can back up into the headliner and flow down under the cabin. Additionally, cracked windshield sealant may let water in during heavy rain. For solutions, regularly clean the drain pipes and seals—unclog them when blocked—it's cost-effective and gives peace of mind.
When I first bought my car, I also noticed water under the driver's compartment. Now I know how to check it. First, observe the location of the water: if it's under the front seats, it might be due to a clogged air conditioning drain pipe—just use an air gun to clear it; if it's near the door edges, it's likely a seal strip issue—replace it or use sealant to fix; if it's under the rear seats, the sunroof drain might be blocked. Check the nature of the water: clear and odorless water is from the AC, while slightly oily-smelling water indicates a leak in the heater core's coolant. For prevention, avoid parking under trees to prevent leaf buildup, and clean the drain outlets during car washes. I personally use thin wire to clear the pipes—simple and effective, saving a trip to the repair shop. Regular maintenance of these areas can prevent electrical shorts and vehicle damage.
Cabin water leakage is often related to the air conditioning system. During air conditioning cooling, condensate water should drain normally, but blocked pipes can cause water to backflow into the compartment. Heater core leaks are also common, with coolant leaking onto the floor. Failed seals, such as aged door rubber or sunroof issues, allow rainwater to seep in. Pay attention to these points during daily driving, and keeping pipes clear is key.
