Young children need 44 to 88 fluid ounces per day to prevent dehydration due to diarrhea or other causes. This amount may vary, depending upon a number of factors, according to HealthDay.
Administration of electrolyte fluids -- such as Pediasure, given in small doses and interchanged with water -- is beneficial in preventing dehydration, advises HealthDay. Because infants with diarrhea can become severely dehydrated in less than 24 hours, parents must monitor them closely. If an infant with diarrhea develops dark-colored urine or sticky saliva, his diaper is consistently dry, he is weak or he has cool mottled hands or feet, he requires immediate medical attention.