What's wrong with aspartame. Sounds like you've been reading some of the scare items on the web that may not be based on valid research?Flavoured water is ok as it doesn't have the dreaded aspartame. I like to make my own flavoured water with slices of cucumber or fruit without the added chemicals, just fruit or veg or both and water.
Have you got a meter @Eddie_S? That might help you decide.
There are so many types of flavoured water so if you say which one you are going to try then someone will advise you of their experience with it or as to why it may not be suitable.
Here you go Eddie http://www.trederwensprings.co.uk/products/flavour500.html no carbs so you are fine with that drinkEssence apple flavoured water