Water on passenger interior floor

Is it water or antifreeze?Antifreeze will feel slick and that would be your heater core. If it's water the drain hole for the a/c is plugged. To locate drain look under hood and lower part of firewall near the bottom you will see a little hose coming out of the firewall.Carefully use a piece of wire and insert in drain and try to unplug it.

Seal is bad around a window or a hole in the floor

Has it been raining where you live or washed your car recently??If not more than likely its your AC drain hose either clogged or damaged. Its located under the passenger dash. Hopefully this helps