Water leakage from the back of Lincoln Zephyr 2006

Is it water or is it leaked coolant? Is it a constant leak in dry weather, or does it appear after running the AC, or does it leak after it rains or shortly thereafter? Leaked coolant: the only thing that would cause coolant to leak this far back in your car is a leaky heater core, with the coolant running under the floor covering until it finds an exit. I do know Lincoln Zephyrs had a problem with heater cores leaking due to electrolysis. But the chance of this size a leak going unnoticed are pretty slim. The other is water from the runoff channels around your rear window and trunk being blocked with debris, and slowly working it's way out after a rainfall. I don't think condensation from running the AC would drip from this far back on the vehicle. But if the 'leak' appears after running the AC, then that might be the cause. Last one is water condensation coming from the tailpipe, but that image doesn't appear to be near the tailpipe, unless it's from a joint between tailpipe and muffler.

Thank you so much Ken for your help! It is clear, cool water and doesn't smell. I live in a very dry and hot weather (Southern California). The water started to come out when I started the car. Today, it leaked much less than yesterday and after a bit it stopped. There was no sign of leakage from the front of the car. The water temperature stayed constant after leaving my car on for about 10 min. I checked the AC and it is working. Do you think it is probably from condensation from running the AC? Thanks!

The AC condensation drain is in the heater box, in the middle center of the dash. If the drain gets fouled up condensation from the AC evap coil can collect in the heater box until it spills over into the cab. I don't see that causing a leak to appear that far back in the vehicle, unless that is where the condensation drain outlet is (usually those are just down along the firewall from the heater box). Unless your Zephyr has a secondary heater/AC for a dual/rear zone (and maybe heated/cooled seats?) As long as it is pure water, and not coolant, it's more of an annoyance than potentially damaging to the engine.

Yes my car has heated/cooled seats. Thank you so much for all your help! :)