I have a water leak in my 1990 honda prelude?

Water leaks onto floor in back seat of my 1990 honda prelude si

The foam seal around the tail lights are a favorite trouble spots for Honda leaks. If you put newspaper inside under them (to show up water easily) and hose them down you can test the seals.

Apart from screen and door seals, if it has a sunroof then check the seal and look for drainage direct to ground from small a watering can around the 4 corners.

If all else fails then get some smoke in the closed car under positive pressure of the air blower and watch and smell for where it comes out. (Incense stick could be best).

These can be hard to pinpoint. Is boot ok? Is screen seal damaged?
Try removing seat. Go through car wash and check for ingress. Us it coming in via a failed seam? Door seal?
If we can pinpoint one side? We can try talcum powder and high pressure jet wash.