A woman named Isa got a nasty surprise when she found her Subaru Crosstrek covered in wet mud stains inside. She had no idea what caused it, so she asked for help on Reddit. That’s when she learned about a part of her car she never knew needed regular care. Isa shared a TikTok video, showing the mess in her car. Water had backed up from her sunroof drains, which were blocked. The water had nowhere to go, so it spilled over and left dirty stains all over her car’s ceiling. When she posted about it online, tons of other people said they had never heard of sunroof drains either. “So was someone gonna tell me that if you have a sunroof, there’s a sunroof drain?” she asked in the video. Plenty of people in the comments were just as confused as she was. One person even said, “There’s no such thing as a sunroof drain.” Isa joked back that she would tell the mechanics in the comments they must have made the whole thing up. Most people have no clue how sunroofs actually work Here’s something that might surprise you. Sunroofs don’t actually keep all the water out. They’re built to let a little bit of water through, especially the big glass ones that cover most of the roof. That’s totally normal. The trick is that there’s a hidden system of small tubes that’s supposed to carry that water away from your car. These tubes sit in the corners of your sunroof. They run down the sides of your car near the windshield and come out by the front wheels. When they’re working right, you never even know they exist. But when leaves, dirt, or other junk blocks them up, the water gets trapped and starts leaking into your car instead. @bbell1017 Distraught is an understatement ((EDIT PLS READ: I’ve never had a sun roof SUE ME I now know it’s a regular thing to maintain NOW that this has happened. We live and we learn my dudes but the drain hose is not common knowledge. I’ll own up to a little bit of ignorance but I’m trying to do better for my car )) #subaru #sunroof #subarucrosstrek #fypシ #fml ♬ original sound – Isa The damage can get really bad. You might end up with a wet ceiling, soaking wet carpet, puddles on the floor, mold growing inside your car, or even broken electronics. If you ignore it long enough, the water can actually rust out parts of your car’s frame. People who fix cars for a living say you should check these drains at least twice a year. This is extra important if you park outside near trees. Checking the drains isn’t hard to do. Just open your sunroof and look for tiny holes in the corners. Pour about a cup of water into each hole and see if it comes out near your wheels. If the water just sits there instead of draining out, you’ve got a clog. Most people clean them out with either the plastic string from a weed trimmer or an air compressor set to low power. When Isa asked for help online, mechanics jumped in with tips while other drivers told their own stories about finding water in their cars. Almost everyone agreed that nobody ever tells you about this when you buy a car or get it serviced. These kinds of unexpected car problems can catch any owner off guard, but knowing about them ahead of time can save you a lot of trouble. Isa wrote in her post, “I now know it’s a regular thing to maintain NOW that this has happened.” Her story shows that owning a car means dealing with stuff you never saw coming, but a little bit of upkeep can stop big problems before they start.