Damp patch on the rear seat floor after every car wash, sunroof drain or door seal
Quote from Patrick Reed on April 29, 2026, 1:02 pmEvery time I take my 2017 530i through a proper car wash or even just hose it down at home, there's a small damp patch that appears on the rear passenger side carpet near the door sill, and it's been slowly getting worse over the last few months to the point where I can actually feel the carpet squish under my fingers after a wash. The headliner is bone dry and there's no water staining around the sunroof or the A pillars so I'm leaning away from a clogged sunroof drain and more toward a door seal or the vapour barrier behind the door card letting water through when it runs down the window channel. I've had door vapour barriers fail on previous cars and it always starts with a damp carpet near the sill, but I was hoping a five year old BMW wouldn't have the same issue just yet. I was on bmw-garage.ae reading about common water leak points and a few people mentioned the rear door drain holes getting clogged with dust and waxy residue which causes water to back up inside the door cavity and eventually seep past the barrier into the cabin. Before I start pulling door cards off or poking around the sunroof drains, has anyone else traced a rear footwell leak on a G30 and can tell me the most likely culprit so I don't waste time chasing the wrong thing.
Every time I take my 2017 530i through a proper car wash or even just hose it down at home, there's a small damp patch that appears on the rear passenger side carpet near the door sill, and it's been slowly getting worse over the last few months to the point where I can actually feel the carpet squish under my fingers after a wash. The headliner is bone dry and there's no water staining around the sunroof or the A pillars so I'm leaning away from a clogged sunroof drain and more toward a door seal or the vapour barrier behind the door card letting water through when it runs down the window channel. I've had door vapour barriers fail on previous cars and it always starts with a damp carpet near the sill, but I was hoping a five year old BMW wouldn't have the same issue just yet. I was on bmw-garage.ae reading about common water leak points and a few people mentioned the rear door drain holes getting clogged with dust and waxy residue which causes water to back up inside the door cavity and eventually seep past the barrier into the cabin. Before I start pulling door cards off or poking around the sunroof drains, has anyone else traced a rear footwell leak on a G30 and can tell me the most likely culprit so I don't waste time chasing the wrong thing.