Sweet and Tangy Loose BBQ Beef Sandwich

7 LBS Beef roast
1 cup water
3TBSP vinegar
4 TBSP brown sugar
2 tsp dry mustard
4 TBSP Worcestershire sauce
3 cups ketchup
2 tsp salt
3/4 tsp black pepper
1/4 tsp cayenne pepper
6 cloves garlic

Put roast in slow cooker along with the water and cook on low for 2-4 hours (till it can be shredded)
Shred with fork, Add rest of ingredients and stir to cover meat and continue to cook on low for 4-6 hours. Serve on buns