Hi,
Seems like a case where
Oral Rehydration Solution (ORS, like Pedialyte)
would have helped prevent dehydration.

1 litre water (5 cups),
1/2 level teaspoon salt(2.5 grams),
6 level teaspoons sugar(24grams).

I just measured ,
half litre plastic water bottle cap holds about 1 teaspoon (5mL)
2 litre soda bottle cap holds about 1.8 teaspoon (9mL)

This new formula [url=ttp://rehydrate.org/ors/low-osmolarity-ors-qa.htm#1]reduces emissions[/url], old formula is 1 litre water 1 teaspoon salt 8 teaspoon sugar