Water on the floor, both driver side and passenger side?

Make sure it is just water and not antifreeze, If just water check in the engine compartment to see if there are any small areas that the water can come in. Check by the kick panels for moisture. Have you gone through any deep water? Also around under the car by the wheel wells. With 345,000 miles also check the rubber seals by the dash. If it has a antifreeze smell your heater core may be leaking. Some auto stores have a pressure check to use in case it is anti freeze. Let me know what you find, Mike

Elizabeth, what did you find out? was it just water?