I want to know how many litres of water can I give my 9 months baby boy?
The fluids intake for an 8kg child is 800ml for 24 hours inclusive of drinks like milk.
You are the one giving child water... So definitely you control what quantity the child takes... Kindly give water only after feeding... usually formula and cereals and for a baby that is well-fed there is limit to amount of water the stomach can accommodate after feeding.... The calculated amount is just a guide
You didn't state the weight of your child. Water intake for a baby below one year is 100ml X baby's weight. Note also that It is all fluid intake... not just water only.