In what way is it unhealthy? Aspartame has zero calories, and decades of studies showing its safety.
Put another way, if you want to avoid sugar (which is much less healthy than aspartame), besides water, there's tea, coffee, flavoring mixes like Crystal Light, and various prepared sugar free soft drinks. Many prefer variety over water. There's little scientific basis to believe drinking any of these things are bad. Drinking a mix of these is quite a bit healthier for an adult than chugging juice or sugared drinks - unless you're explicilty trying to carb-load. Milk is a healthy alternative but debatable due to its effects on some.
