What Are the Causes of Water Leakage in a Car Trunk?

[AmyFitz]

Water leakage in the trunk can be caused by the following reasons: 1. Worn or Aged Sealing Strips: Worn or aged sealing strips, or trunk deformation, can lead to water leakage. It is necessary to check whether the tailgate rubber strip shows signs of aging, wear, or cracking. If the vehicle has been involved in an accident before and leaks after repair, check whether the sealing rubber strip applied post-repair is not tight enough or if there are cracks in the repaired area. 2. Detached or Damaged Sealing Strips: If the sealing strip around the rear taillight connector becomes detached or damaged, water can flow into the trunk from the taillight. 3. Leaking or Clogged Drain Pipes: Some cars have sunroof drain pipes running through the trunk. If these drain pipes leak or become clogged, it can also cause this issue.

[MatthewDella]

I recently dealt with a water leakage issue in my own car and found that trunk leaks are quite common. The main culprit is the aging and deformation of the sealing strip. Rubber materials tend to harden and crack after five or six years of use, making the trunk appear tightly closed but actually leaving gaps. Rainwater then seeps in along the car frame. Another issue is the drainage holes getting clogged with leaves and mud, preventing wash water from draining and causing it to seep into the spare tire well. If you notice a musty smell or water stains under the spare tire, chances are this is the problem. When inspecting it yourself, focus on checking for cracks in the sealing strip and any water stains along the trunk edges. Prolonged leakage can lead to rusting through the chassis, so it's important to address it promptly once discovered.

[ZoeyFitz]

Last time I helped my neighbor check his leaking car, and found it was caused by aftermarket modifications. He had installed a reverse camera by drilling holes near the license plate lights for wiring, but the sealant wasn't applied properly during installation. When it rained, water seeped along the wires into the spare tire well. Audio system modifications can also cause issues - like when amplifier power cables are routed through trunk gaps, damaging the factory waterproofing. Actually, OEM designs all have waterproof channels, so special attention must be paid to sealant quality when doing DIY modifications. I recommend doing a water splash test after modifications, and immediately reapplying sealant if any issues are found. Otherwise, water exposure to wiring can cause short circuits and bigger problems.

[EmeryAnn]

I've seen many older car trunks prone to leaking, mainly due to issues with the sheet metal seams. For example, the installation area of the rear light clusters—over time, the rubber seals age and crack, allowing water to seep in when blasted by a high-pressure car wash hose. Another common spot is the weld points around the rear windshield, where the sealant degrades with age. The trickiest cases are cars that have been rear-ended; if the trunk lid wasn’t properly realigned during repairs, it may not close tightly. To check yourself, use a flashlight to inspect the inner side of the seals—look for light shining through gaps. A simpler method: place a white sheet of paper in the trunk on a rainy day and check later for dampness.