wet floor on drivers side

Do you have A/C? if so, the condensation drain for the heater-A/C enclosure may be plugged and condensation (or rainwater - with or without A/C) is collecting there and leaking out onto the floor. the drain is usually a rubber hose that goes from the bottom of the enclosure thru the firewall to drain onto the ground under the car. That's if the wetness is water. If the wetness is coolant, then you probably have a leaking heater core and that will have to be replaced.