The usual cause is a condensate drain that is plugged. You should be able to crawl under the car and poke something up through the drain to clear it out. Another possible problem is the drain pan is cracked or broken allowing the condensate to drip. This would require partial disassembly of the dash to replace.
Heater core leaking?
The leak may be coming from the neighboring condo's bathroom. Pipes run all over - they can leak and come up through the floor or through the walls or ANYTHING. Better get a professional. Should be the associations responsibility.
If the drain plug under the evaporator coil is plugged up it will cause condensation to leak into the car. If the heater core is bad it will allow coolant to leak into the car. If the leak is warm and smells sweet it is the heater coil.
Evaporator drain plugged? try to run a flexible wire coat hanger etc. or low pressure air up through drain to unplug
The obvious answer would be that there would be a leak somewhere...
Typically that leak is caused by a leak in the heating system. The heater core is under the dashboard, just above the passenger side.
Condensate drain plugged or disconnected
Wet passenger flood is caused by either a leak in the air conditioning drain line or a leak in the windshield sealant or a coolant leak coming from the heater core.
water in passenger floorboard, where is the hose that would cause this?
Are you running the air conditioner? If the drain line is plugged, it will leak water (condensation) onto the passenger side floor.
Heater core leaking?
Probably have a leak in the heater core>
It probably has a leak in the heater core.
Leak in heater core
either a ruptured heater core or a bad hose/ connection on either end, either way u have to take it out.
IT IS LOCATED ON THE PASSANGER SIDE OF THE VEHICLE, WHEN THEY DO LEAK THEY TYPICALLY LEAK INSIDE THE VEHICLE.
There is obviously a leak in either the firewall/cowl area or the window seal.