water leak

If it tastes like water, I would guess it is condensation from the back seat A/C. This water is supposed to drain out on the ground so check for a plugged drain tube. There is also a chance the moon roof leaks or somebody left it open and made sure you didn't find out until now.

I just found and fixed the flooding passenger floor of my customers 2014 Lincoln MKS. I thought it was a A/C condensation problem. However, I never found the A/C drain. What I found was that the rain water drain tubes on each side of the car were Clogged solid with broken down leaves and debris. So, I removed the wiper blades, then the upper shield and then the lower shield to gain access to the problem. The problem begins with owners allowing leaves to accumulate under the hood. Then, when it rains these leaves are pushed further under the shields. Then it can't be removed easily without removing these parts. What I found that was causing the Water Leak in the Floorboard was the clogged drain tubes caused rain water to rise above the fresh air inlet on the passenger side of the car. During a heavy rain the water rose faster than the clogged drain tubes can get rid of it. I cleaned out the tubes and vacuumed as much of the leaves and debris out as I could. Then, I rinsed the remaining debris down the drain tube openings and then reinstalled the tubes. I reassembled the lower and upper shields and the wiper blades. Then, I ran water on the windshield two different times checking for leaking inside the car. No More Leaking. I took about 2 - 1/2 hours to disassemble, clean and then reassemble the car. You'll, also want to pull up the carpet to remove as much of the water as possible from below the carpet. There is lot of water trapped under the carpet, that will need time to dry out.