Well everything is a chemical if you want to be really technical about it

- down to the plastic in the cups and the wood in the trees.
I meant artificial food additives and just used a generic term - apologies if I wasn't specific enough

.
I personally believe in moderation for LOs - especially when they are having very picky phases. I do use childrens yoghurts, for example, and the odd fruit shoot if we are out and their drinks have run out etc etc.
Back to op's question - no I would not feel comfortable with 'no alternative' to a drink in one of my LOs either - I would just move to using diluted real orange or apple juice - and encourage water as well.
Actually when DS was younger and very fruit juice dependent what I started to do was insist on water a certain times of the day. So after tea all he can have is water or a cup of milk before bed. At meals it is water, but juice for snacks. That way he knows what to expect and that seems to work fine. I think he may have been a bit older than 20 mths when I started this, but it may help if you feel your LOs comprehension level is good enough.
But honestly - just make slow changes until you are doing something you are comfortable with

. We all have different approaches to food etc in our children really

.