Diluted juice stored in fridge for kids

My daughter loves diluting juice. We have been trying to wean her off by giving her gradually weaker juice until hopefully it's barely coloured water. To do this we have been making up large bottles of diluted juice in empty bottles and storing them in the fridge. Every time one bottle of the diluting juice is finished we have a new supply so it means we are only re-using the bottle for a short time.

Bonus 1 - Can control the strength of the drink (does not vary with each drink depending who prepares it).
Bonus 2 - Easier to get drink when required (My daughter always seems to ask when I'm in the middle of feeding her brother or cooking etc)