I asked about my 1year 6months old daughter who drinks 1.5 liters/day i got the answer that itis too much so what's the usual amount she should drink?

About 32 ox/24 hours: The average amount of fluid that a child of this age might drink should be around 32 oz/24 hrs. This is not a hard and fast number, however. I does not take into account activity level, local conditions (hot weather), etc. One concern of drinking so much fluid is that the child will not eat solids and suffer nutritionally as a result.

See detailed answer: If an 18month old drinks too much water it can fill them up and they don't eat enough nutritional food needed for growth. She needs food with calories and nutrition. A few glasses of water is fine but not 1.5l. If it's a new increase in thirst recently then she should be evaluated.