heater core leaking
If it's the front passenger side ,I would say your heater core is leaking .
This would be caused by a leaking heater core, or a leak in the plumbing associated with it.
Leaking from the water pump at the back on the passenger side.
Radiator or hose but probably water pump
its water make sure the drain hole for the AC is not cloged
It could be the heater core leaking.
It can be one of 3 things. My first guess would be a leaking heater core considering the area where it is leaking. Are you sure this is water and not coolant. If it tastes sweet or is slick to the touch, it is coolant and you have a leaking heater core that must be replaced. Secondly it can be the windshield seal that is leaking. And 3rd it may be that the drain holes below the windshield cowl are stopped up allowing water to enter the passenger compartment.
If you have your air conditioning running it is the moisture that is pulled out of the air when it is being cooled. That water is then expelled outside of the car
This is an indication that your heater core is leaking. To stop the leaking you will have to replace the heater core or stop using your heater.
The ac drain is plugged. The drain hose is on the firewall on the lower passenger side. ...that, or your heater core is leaking.
Would that be when it is raining ? If so you need to caulk around the vent in the fire wall area. If not from rain, then the heater core is leaking, and you will be losing coolant.