Backwater intrusion

I’ve been doing something new for me since I was driving a car… I’ve always been driving a plastic stacking box with tools in the back left in the hold… About 2 weeks ago, when the sun was burning and I crawled in the box, file myself, which was there abundant (so 3-4cm) water in the box. Where the hell does that come from??? I had no explanation at all – not at all because the sun had been shining for days. Yesterday I put a box of beer in the back and look at my hold mat: wet ! And in de r box was soup again ! Where does that come from ? One might think that I forgot to close the flap and it rained in … or someone pours flowers in my car ? Everything dry in disguise, slices and sky ! At least I could not recognize anything eye-catching at first. And with the amount of water in the box the other day would have to be a more or less huge hole somewhere . Moreover it must come somehow from above – how else should it come into the box ? I don’t think it’s the sunroof. A) If I’d already wet the seats and B) the water is in the back … I don’t think it is / can be the sunroof. A) If I had already wet the seats and B) the water is in the back …