What Causes Water Under the Rear Seat Car Mat?
2 Answers
Water under the rear seat car mat may be caused by various reasons such as a leaking drain plug at the bottom of the car compartment, a leaking sunroof drain pipe, a leaking door, a leaking heater core (causing antifreeze leakage), a damaged or improperly installed air conditioning drain pipe, among other possibilities. There are multiple potential causes: sunroof leakage due to poor sealing—check the sunroof; water from car washing that wasn’t properly cleaned; or rust in the car’s small radiator (used for cabin heating), leading to leakage. To check if the sunroof drain pipe is clogged, fully open the sunroof to reveal a groove. Slowly pour water into this groove (the sunroof drain pipe) and observe whether the water drains properly or is blocked.
Last time there was water under the rear seat floor mat in my car, and it turned out the sunroof drain was clogged. I poured a bucket of water on the roof, and it leaked into the cabin. Aging door seal strips are also a common cause—during heavy summer rains, water seeps in through the gaps. When checking, first remove the floor mat and use a flashlight to inspect the gaps for obvious signs. If there’s a lot of standing water, quickly soak it up with a towel to prevent damage to wiring or moldy carpets. Handling this yourself can be troublesome, so it’s best to visit a repair shop to clean the drainage pipes or replace the seals—it’s inexpensive, costing just around 100-200 yuan. Additionally, damaged door sills can also cause leaks, so pay attention to water stains during regular car washes to prevent issues early.