Water getting into 2001 Honda Insight

Water occasionally gets into my 2001 Honda Insight after a rainy or snowy day. I am worried that it might be going somewhere dangerous. But I am also worried I might spend a lot of money trying to fix it, and I may not know if it is really fixed because the problem is so intermittent. At first I would occasionally see a tiny puddle - maybe 1/4 cup of water below the right rear window. But twice I have found the seatbelt wet in the morning. So now I am worried the water might be going somewhere I don’t know about. A couple of people have asked me if the car was in an accident. I bought it second hand. Car Fax does not find any accident on it. Any ideas?

Got a sun roof?  My guess is the right rear drain is clogged.  Not difficult to figure out and usually is cheap to fix.

Which seatbelt is wet?

Driver’s seatbelt.

Does it have a sunroof? Sunroof leaks seldom show up at the sunroof, but they are the #1 source of cabin leaks.

It does not have a sunroof.

This is just a WAG but there MAY be a crack in a weld that allows water in.

The crack may open with body flexing when the vehicle is in motion then leak when parked.

If you leave the vehicle parked (overnight) during a rain, is the seatbelt ‘freshly’ wet the next day? The complete belt, top, bottom section or what?

BTW it is not really dangerous. But I would still want it fixed.