If it is just plain water, then you have either a leaking windshield or more than likely a stopped up A/C drain line. Look under the car passenger side and find the drain line and unclog it. If, on the other hand you have coolant leaking, then you have a leaking heater core, which must be replaced. Taste and smell the liquid. If it smells and taste sweet it is coolant and not just water.
If it is coming from the tank: NO. If it coming from the bowl: YES!
I had the same problem and fixed it. Your air conditioner run off tube is plugged. It is located on the drivers side on the floor near the center console. It is in the corner of the floor board. If you pull the carpet up, you will see a plastic L shaped tube. To fix the problem, just drill a hole in this tube, and put a clothes hanger into the hole to release the clog. After that, fill the hole with Epoxy.
pull up the carpet on the drivers side rear floor and see if theres water. We just had this problem, the water shorted out the brakelight which cost $750.00 @ the dealership. Still having water coming in!
with a towel
Take the 1998 4-Runner to a car wash. Have a helper sit inside while you spray the windows, doors, and under the vehicle to find where the water is coming in from.
check the drain line on the a/c or does it have antifreeze smell to it then it could be the heater core
any leak on your drivers door, or firewall. could be just about anything.
It could be coming from your heater core, may need to repair or replace it.
sounds like it could be a bad heater core. that usually leaks into the passanger side floor.
I would check your AC evaporator drain tube , if clogged water will drip on floor.
Heater Core is the likely culprit
If it's not related to outside weather, then check the drain for your AC condenser.