Water on the drivers side floor board. No visible leaks at the weatherstripping. The leak appears to be concentrated in the center of the floorboard. Any ideas???

https://www.club3g.com/threads/water-in-driver-side-floorboard.261515/

https://repairpal.com/ac-is-leaking-water-into-the-driver-side-floor-113

How is the coolant level ?

It sounds like a severe heater core leak,that why I ask if your coolant level is always low?

You have rubber plugs under the cars body that could allow water to enter but if you have standing water that cant be it.

Does it only happen when it rains ?

Does the trunk area get wet ?

If you have a sunroof it could be the drain that follows the front pillar letting out under the front fender. These hoses are known to plug and crack open releasing water into the floorboards.

Driver side door check along top and front edge for tears or twisted looses sections. Internal to the door water can drain down along the window and is released outside the door seal. If the bottom of the door has the opening that releases the water plugged then water will drain over into the floorboard.

Is underneath your car rusted

Looks like you may need new weatherstrip for the driver's door including the pieces for the window.

My brother had the same problem with his pontic grand am, only it was the front windshield but all he had to do is get the proper weatherstripping and put it in. It solved the problem of rain leaking into the front pass. floorboard. I dont know if that will solve your problem but its worth a shot right???? Goodluck

Check the weatherstripping around the door. Also look under the dash board for signs of water leaking from the firewall. If your weatherstripping isn't damaged anywhere then make sure the liquid doesn't smell like antifreeze. If it does then you've busted the heater coil. Do not drive the car if this is the case. Your coolant will all leak into the car and it will overheat. Replacing a heater coil tend to be a huge pain in the **** and if you can pay someone else to do it by all means do. The heater coil can be bypassed by connecting the water inlet hose to the outlet hose where they go into the firewall. This is a crutch but your car will run fine until you can get the heater coil replaced. A mechanic will do the bypass for you pretty cheaply. It only takes 5 minutes.

I had a similar leak on a 1995 Accord. I traced the issue to the plastic liner behind the door panel. The seal was broken at the bottom and water would leak from that to the rubber weatherstrip at the bottom of the door that seals at the plastic threshold molding. You can't really see it good until the door panel is removed. The water would drip until it puddled up enough to run over the threshold molding and under the driver's seat. This caused the floorboard behind the driver's seat to be soaked after a rain. I have resealed the plastic lining but of course it hasn't rained since. I'm confident this will solve my problem and hopefully provide you a new place to look for yours.

the ac drain is clogged up,so it does not drain outside,check pass.side-pull carpet away from fire wall and padding should be wet

Engine coolant will feel oily and the windshield will fog up and the car will stink. If it is just water it could be coming from the passenger door weatherstrip at top. The ac drain tube , if stopped up will also leak water in the floorboard.