aspertame is some horrible artificial sweetener that is supposed to cause cancer or something. my ob's office recommends avoiding anything with aspertame as an ingredient.
the la croix water is available on amazon if you can't find it there. they don't have the plain kind available, but they have some flavored ones. it's all natural flavoring. if i can't find the plain at the store, i usually buy the lemon one...makes a great mixer.