Put the barbecue sauce ingredients into a bowl and mix well.
Pour the water into the bottom of the slow cooker. Add your chicken leg quarters to the slow cooker and then top with the sliced onions.
Pour the sauce on top of the chicken and onions.
Cover the slow cooker and cook on high for 4 hours or low for 6 hours.
HINT: I created this slow cooker chicken quarters recipe to be a dump-and-go recipe because I wanted it to be the easiest possible. If you like a browned finish for your chicken, I would encourage you to brown the chicken in a hot oiled skillet on each side for 4 minutes before adding it to the slow cooker.
Enjoy hot. You can add potatoes and carrots if you would like to slow cook some vegetables with the chicken.
Notes
You can use chicken leg quarters, chicken legs, or any bone-in chicken pieces you have on hand.
If you like your chicken really saucy, double the barbecue sauce recipe.
This chicken dinner will keep fresh for up to 4 days in an air-tight container.
You can freeze this chicken easily in a freezer-safe zip-style bag.