Glad you found the problem!
Yes, the water line is a standard 1/4" tubing.
Not sure how your setup is, but you may want to run a copper line to the refrigerator instead of another plastic one.
Also if the water shut off is right behind the refrigerator you may want to use a stainless steel braided water line.
Just don't install a flood safe water inlet hose as I have had trouble with them not working correctly.