I have a trunk leak in my 90 accord on the drivers side. My antenna is not in good shape so I dripped water down the shaft and sure enough it all went into the trunk.

The water spreads and puddles in other places so it looks like a huge leak.

You would be amazed how much water gets in from just dripping off the antenna but I have quite a puddle in my car after it sat over the weekend during the rain.

I have not replaced the antenna yet but I believe it may solve the problem.