I went to replace my water filter in my new home on my whirlpool refrigerator and found out that it doesn't have one. There is only an ice maker. I was told that it gets installed outside the refrigerator and mounted outside. I am not sure how to do this, plus the line in is a good water hose that's is bigger and stronger than the normal refill lines.

All you do is buy a good water filter and with it you buy adapters to match the water line going in your refrigerator. It's very easy to do with a little help from a salesperson at Lowe's or Home Depot.