What is the problem with water on the floor of a sedan?

[AlinaAnn]

It may be due to rust perforation in the chassis or water splashing in from the wheels. Below is relevant information about automobiles: 1. Definition of an automobile: According to the latest national standard in China, "Terms and Definitions of Types of Automobiles and Trailers" (GB/T3730.1-2001), an automobile is defined as follows: a non-track vehicle powered by an engine, with four or more wheels, mainly used for transporting people and/or goods; towing vehicles for transporting people and/or goods; or for special purposes. 2. Introduction to domestic automobile brands: Domestic automobile brands include Hongqi, Changan, Great Wall, Chery, Geely, Roewe, BYD, etc.

[DelDaniella]

Recently, there's been water accumulating on the front passenger floor of my car, and it took me a while to figure out why. In summer, when the air conditioning is on, the evaporator generates condensation, which should normally drain out through the undercarriage drain tube. If the drain tube is clogged or detached, the water can backflow into the car. Another common issue is when the sunroof drain holes get blocked by leaves, causing rainwater to flow down the A-pillar and soak the carpet underneath—this needs immediate attention. A friend of mine had his car flooded, and the floor wiring harness rusted completely, costing nearly ten thousand yuan in repairs. My advice is to first remove the floor mats to ventilate and dry the area, then use an air gun to clear the drain holes. If the water has a sweet smell, it's essential to check the coolant reservoir.

[LaValerie]

I've also researched the issue of water accumulation in the car floorboard for a while. The most easily overlooked cause is the aging of door seals, especially the seals at the bottom of the rear seats. A small crack can let car wash water seep in. I remember once after rain, I found the rear seat carpet moldy, and upon disassembly, it turned out to be a failed rear taillight gasket. For DIY solutions, first use a dry towel to absorb the water, then use dehumidifying bags to remove moisture. Leaving it unresolved long-term can lead to rust penetration of the chassis. A colleague's decade-old car had to replace the entire floor panel at a cost of several thousand due to excessive water accumulation - truly not worth the loss.

[DiEden]

Last time I washed my car, I found a puddle of water under the driver's seat, which scared me into immediately checking the cause. First, I checked if the drainage channel under the windshield was clogged. If it's filled with leaves, rainwater can backflow into the air intake. Then, I checked if any aftermarket devices like dashcams were installed. Many aftermarket devices require wiring through the firewall, and improper installation can leave gaps. Finally, I thought about the vehicle's water wading situation. After wading through water, it's important to ensure the door frame drainage holes are clear. At that time, I found the front windshield drainage channel was completely blocked by dead leaves. After cleaning it, the problem was immediately resolved, taking less than half an hour in total.

[RonanFitz]

From my experience, floor water accumulation should be checked in stages. If it occurs after using the AC, it's usually due to a clogged AC drain pipe. For water after rain, focus on inspecting the sunroof drains or window seals. Post-car wash leaks point to damaged door waterproof membranes. Once during maintenance, a mechanic used an endoscope and found my rear floor leak was actually caused by a small stone stuck in the trunk drain valve. Remember - standing water over three days breeds mold and bacteria, especially concerning for families with children. Health concerns outweigh repair costs every time.

[DelElizabeth]

I have personal experience with this issue. Last year during the rainy season, there was always a musty smell in the cabin. When I lifted the carpet, I discovered a five-centimeter accumulation of water in the spare tire well. The reason was unexpected: the welds on the underbody steel plate had aged and were leaking. Older cars are most prone to this problem, especially those over six years old that haven't had underbody coating. To fix it, you have to remove all the seats and expose the area to sunlight for three days; otherwise, the sponge padding will absorb all the moisture. By the way, most sunroof leakage cases are due to aging or detached drainage pipe connectors. Replacing them with silicone connectors costs just a few dozen yuan, which is much more cost-effective than a major repair.