
A car has six drainage outlets. They are the door drainage outlet, sunroof drainage outlet, fuel tank cap drainage outlet, air conditioning drainage outlet, engine compartment drainage outlet, and trunk drainage outlet. Door drainage outlet: Most cars have at least two door drainage outlets, located at the lower part of the door panel. When it rains, water drains out from here. These drainage outlets are often overlooked due to their low position. Sunroof drainage outlet: The sunroof drainage outlets are located in the four corners of the sunroof and can be seen when the sunroof is opened. This design is crucial for rainy days. The sunroof drainage outlets must not be blocked by debris; otherwise, rainwater can easily seep into the car, causing electrical issues. Fuel tank cap drainage outlet: Located beneath the fuel tank filler cap. Some cars have fuel tanks that are not perfectly sealed, creating a concave space. Hence, this drainage outlet is designed. It is important to ensure this outlet remains unblocked. Air conditioning drainage outlet: The air conditioning drainage outlet varies by car model. If blocked, it must be cleared using a thin screwdriver from the car's undercarriage. The degree of blockage may vary. Engine compartment drainage outlet: The engine compartment has drainage outlets and channels that help keep it dry. The drainage outlets are large and prone to debris accumulation, requiring regular cleaning. These outlets are highly susceptible to blockage and are very close to the air conditioning intake. Due to the high temperatures in the engine compartment, bacteria can grow and potentially enter the car's interior through the air conditioning system. Trunk drainage outlet: The trunk drainage outlet is positioned very low. If the car is submerged in water beyond a certain level, water may flow into the trunk through the body structure. To use it, simply unscrew the outlet. If any drainage outlet is blocked, it can cause significant problems for the car, ranging from minor to severe damage. Therefore, prevention and regular maintenance are more effective than dealing with the consequences.

I noticed there are quite a few drainage holes on cars. The main one is a small hole at the bottom of the windshield under the hood to drain rainwater and prevent pooling. Each door has a drainage hole at the bottom, located inside the door seam to let out any water that gets in. There are fine drainage slots around the sunroof frame for rainwater. Near the trunk or rear bumper, there might be drainage tubes to handle accumulated water. If these get clogged, water can enter the car and cause mold or rust. Every time I wash my car, I use a small wire to gently clear out any debris to keep them flowing freely, which gives me peace of mind. I recommend checking and cleaning them regularly to avoid musty odors and expensive repairs—don’t wait until there’s a flood to panic.

After driving for twenty years, I know that drainage holes are hidden in several key locations: The holes at the bottom of the doors are crucial for draining accumulated water—once they got clogged, and water flooded into the door frame. The drainage outlets under the windshield near the hood prevent flooding in the engine compartment. The sunroof drainage tubes are at the end of the tracks. There might also be drainage designs near the trunk. If clogged, not only does the car get damp inside, but it can also corrode metal parts. I regularly use compressed air to blow them out—it’s quick and effortless. Just remember not to apply too much force when cleaning to avoid damaging rubber seals or the paint. Developing good habits saves both money and hassle.

As a car enthusiast, I've noticed that drainage outlet designs vary by vehicle type: sedans have drainage holes on the front windshield for rainwater; SUVs feature more drainage pipes on the roof or sunroof; door bottom positions differ for each model; trunk drainage outlets are usually located under the bumper. When cleaning, I use a soft-bristle brush or water hose to flush them, preventing leaf or mud blockages. Regular inspections can avoid odors or part damage caused by water retention. By the way, remember to use gentle tools to avoid puncturing the interior trim.


