I have an 01 mustang v6. Noticed the other night when I was vacuuming it under my floor mat there is a decent amount of water. It's not coolant just water. But the sides of the floor board are completely dry. Dont see anywhere it would be coming from but doesn't mean it isnt leaking somewhere. Windows and windshield dont leak from what I've noticed. It has rained often the past few weeks. I've never cut the AC on but I do use the defrost every morning. Any ideas??

I'll attach a picture of my floor board

please and thank you. First mustang I've owned so have a bit of learning to go with this one

 

Cowl drains are clogged, if you have a cabin air filter there, that's where it
comes in.

 

I'd agree with it being the hood cowl vents being blocked but on my 2000 v6, i don't have a cabin air filter. I'm not sure how you can be sure it just water but passenger floorboard being wet could also be the heater core leaking coolant. If your mustang has a cabin air filter then it would most likely be the hood cowl drain is clogged

 

Even if you don't have the filter, the air intake is on that side. The drains are
oval rubber flaps. I can't see how they clog up, they're pretty big, and can
easily put your finger through them. 05-'09 You can see the one drain in the
engine on the passenger side. It's right under the battery tray, to the right a little,
and down:



You can see water coming out of it, it is currently raining here.

When these clog up, the water goes in through the blower inlet, filter or not...
A leaf can be over top of it, or just clogged up.

If your heater core is leaking, then it will smell like coolant...

Not sure where your drains are in the cowl, but it has them. Can't find any
pictures on the net, just 2005+