I have a Whirlpool fridge model WRS325FDAM. I'm told it does not come with a water storage tank inside of the firdge that will keep the water line cool when dispensing out of the fridge. Is it possible to add one and if so, what parts do I need?
The simplest answeris to get a container with a dispenser tap and put it in the fridge. I use one of the larger Brita filtered containers, but similar things are available from several companies. This does take up some fridge space, and requires opening the door to pour yourself a glass of water. On the other hand, the added thermal mass of the water may improve the refrigerator's efficiency.
(Yes, I've been pondering what it would take to convine a manufacturer to sell me a unit with cold water tap but no ice maker. Or to create my own.)
Did you ask if it has a water tank or if that the water comes out cold?
Most fridges don't have a tank inside, they have a coiled up length of plastic water line that gets cooled. It may only hold enough water for a few glasses at a time but it will come out cold. IME, no fridge dispenses tepid water.