Where is water in the drivers side floor coming from on 2001 Galant?

If it is just plain water, then you have either a leaking windshield or more than likely a stopped up A/C drain line. Look under the car passenger side and find the drain line and unclog it. If, on the other hand you have coolant leaking, then you have a leaking heater core, which must be replaced. Taste and smell the liquid. If it smells and taste sweet it is coolant and not just water.