I have a 99 civic sedan and it has a trunk leak that its driving me nuts! i have been trying many things and i can't seem to find where its coming from i have put silicone everywhere and let it dry to see if that would have solved my problem but that didn't work i ended up removing the silicone afterwards and i also got my rear window re sealed took it to a window place and they removed it all cleaned it up and put new glue on the rear window thought it would have solved my problem BUT nope did not there was not a single difference and i believe weatherstrip is not the issue so here are the details.....

(PIC #1)Pour Water here

(PIC#2) Water starts to come in thru here inside the trunk. Same goes for the other side even though we are just pouring on the left side it still somehow idk where travels and reaches the other side.

(PIC#3) I figured it was something here so i siliconed it to make sure see whats up did the same for the other side

(PIC#4) as i clearly check where is leaking its wet on both sides inside the trunk BUT i thought water would run from one side to another and i would be able to see it but you see its dry. Although you only wet the left side water runs thru IDK WHERE and reaches the right side and gets it wet inside in the trunk

 

was your car ever in a rear end accident that you know of ???

 

Nope car is a clean title frame is straight matching vins all around

 

well then the trunk weather strip looks in good condition but looks can be deceiving thats where i would start considering that problem point is exactly where water would pool. these problems suck because we cant actually be there to inspect so we can only really send you on a wild goose chase but thats where i would start.