Um, garbage bags. Seems obvious, right? But in times of need, you'll need them for all types of things. Getting rid of refuse, of course, but most essentially they would serve as your receptacle if your toilet stops flushing. In that case, you can either fold them inside the (now empty) toilet, and tie off as needed, or put them inside a bucket.
GLAD 70313 Drawstring Outdoor 30-Gallon Trash Bags
WHERE TO BUY
Bottom line: Not only for the trash, but also key for apartments and suburban locations when your toilet isn't working and going outside isn't an option. See where we're going with this?
Recommended for: Apartments, shelters.
No. of units recommended: 90 bags in this bunch, a good start.
You’ll also need: You might consider a nice bucket.