Deglaze the pan with the water. Pour the water into the hot skillet. Use a wooden spoon or spatula to scrape any "bits" off the bottom of the pan. Pour the water and any "bits" into the slow cooker.
Turn off the heat on the skillet.
Pour the Italian dressing into the slow cooker over the roast.
Add the smashed garlic cloves to the slow cooker.
Cover and cook on low for 6-8 hours, until the roast is fork-tender.