Clear tube

[Slick]

Alright, I am in the process of installing a sound system in my 3Dr. I pulled off the passenger side kick plate and low and behold I found a clear tube running down the side of the interior of the car. My question is... is it rear window washer fluid or fuel line? My first thought was window fluid, however, if this were true then it might/should have a blue tint to it. However, taking into consideration that, like many lightly colored liquids, thin amounts of it would appear clear. So, my only test that I could perform is to start the car, hit the rear window washer button, and then squeeze the tube. So one of two things will happen, the squirter will quit squirting... or the motor will shut off Any help will be appreciated.