Usually when you have that running water sound is when you have your heater on or anything air circulating related. Now from what I've been told, is that when you hear water in your dash like what you are hearing it usually means that the Air conditioner resevoir is filled. And the way that things usually work is the water that is gathered up runs into the resevoir and then runs out a drain that you usually see the water marks on the ground.
The reason that you are hearing water is because the drain is plugged and to un-plug it, put the nozzle of an aircompressor up to the drain which is on the fire wall on the passanger side (near where you are hearing the water). When you blow the air into the drain line, it should un-plug and you should have water pooring out. Good Luck.
Let us know how this works out. I heard this on Car Talk on NPR (National Public Radio), a radio public station around here. I also told this to a friend of mine and he did it on his Lebaron and it did work. So like I said Good Luck.
God I'm Awesome!!!
