Whisk together the water, Italian dressing mix, ranch dressing mix, and brown gravy mix together in a bowl until smooth. Place the beef roast into a slow cooker, and pour the sauce over top.
Cook on Low until the roast is easily pierced by a fork, 6 to 8 hours.
From http://allrecipes.com/recipe/214413/three-packet-slow-cooker-roast/