Place the roast in a lightly grease slow cooker.

In a small bowl, stir together the dressing mixes, gravy mix and water. Pour over roast.

Cover and cook on low for 7-8 hours, or until roast shreds easily with a fork.

Remove roast and cover to keep warm. Drain juices from roast through a strainer into a medium saucepan.

Combine flour and one cup of water. Whisk into pan juices. Bring to a simmer over medium-high heat, stirring often, until thickened. Serve gravy with roast.