The amount of water that a 2 year old should drink everyday is at least 16 ounces of water per day.
That is at least two 8 ounce glasses of water per day is what a 2 year old should be drinking to stay hydrated and healthy.
The 2 year old can drink more than 16 ounces of water per day if they are more thirsty but it's good for them to also drink some milk, juice etc.
But as long as the 2 year old is getting 16 ounces of water per day they will be hydrated enough.
That is unless they are more thirsty as some 2 year olds drink more water than others.
Allow the 2 year old to drink as much as they want.