An Introduction to Water


This article provides an introduction to carbohydrates. Carbohydrates are one of the three macronutrients, a group that also includes protein and fat. This information can be used to understand the complexities of carbohydrates and their role in the body, and to support your discussions with parents on the value of this important nutrient as well as healthy food sources.

As the major component in blood plasma, water helps carry nutrients and oxygen to and from cells. Water is necessary for the digestion of food, the elimination of toxins and waste materials, the circulation of body fluids like blood and lymph, and to help regulate body temperature. Water provides a moist environment for all body tissues and cushions joints and protects tissues and organs.

Daily intake recommendations

Water intake needs for infants and young children are influenced by size, body composition and activity level, as well as the temperature and humidity of the environment. Water is lost continuously through various routes such as exhaled air, perspiration, feces and urine. The continuous evaporation of water from the lungs and skin, known as ‘insensible water loss’, increases at high altitudes and with low humidity.

When water intake is low, the kidneys conserve water and reduce the volume of urine excreted. When there is excess water intake, the kidneys increase both the volume and dilution of urine. In addition to many influences on the consumption of fluids, such as taste and availability, thirst is the most important stimulus affecting the intake of water. Unfortunately, in a state of dehydration, by the time dehydration triggers thirst, body water is already being lost. For this reason, consuming water before activity is particularly important in hot weather.

According to the American Dietetic Association (ADA) and the American Academy of Pediatrics (AAP), breastfed and formula-fed infants usually do not need additional water. It has been estimated that infants need 1.5 mL water/kcal of energy expenditure for adequate intakes; this water-to-energy ratio corresponds to that found in breastmilk and common infant formulas. The AAP suggests that water may be offered to bottle-fed infants older than 6 months, but they may prefer to get extra liquid from more frequent feedings. Breastfed infants generally do not need extra water if they are feeding on demand. In unusually hot weather, infants may need some additional water. Introducing older infants to sips of water may help them learn to drink water to quench thirst. Caution must be used so that water does not displace needed energy and nutrients in the diet.

As complementary foods are introduced around age 4–6 months, the older infant’s need for water increases, and other food and beverage sources including drinking water start to contribute to daily water intake. Water is the best way to keep older infants and children hydrated. During hot months when children lose more fluids, parents can offer water 2 or more times a day. It should be noted that cow’s milk has a high renal solute load, which may increase the risk of dehydration. For the child 12 months+ who is drinking cow’s milk, it is important for parents to ensure that their child is also drinking adequate amounts of water.

Adequate Intakes of water in infancy and early childhood

0 to 6 months 0.7 lieters/day, assumed to come from breastmilk/formula 
7 to 12 months  0.8 liters/day from breastmilk/formula, complementary foods and beverages 
 1 to 3 years 1.3 liters/day from food and beverages including water 
4 to 8 years  1.7 liters/day from foods and beverages including water

Hydration during illness

Of particular importance is maintaining proper hydration during illness. Vomiting and/or diarrhea can lead to dehydration if not balanced by adequate fluid intake. Fever, coughing, rapid breathing, and watery nasal secretion also can dramatically raise the amount of water lost.

The major therapeutic goal of treating diarrhea is to ensure a normal state of hydration. An oral electrolyte solution is a simple, effective and inexpensive treatment for diarrhea-related dehydration. In the body, a balance of electrolytes (or salts), including sodium, potassium and chloride, is essential for normal function of cells and organs. An electrolyte solution that provides a balanced solution of these salts along with sugars such as glucose, dextrose and fructose, is designed to restore electrolyte balance to promote quick fluid and electrolyte absorption. An electrolyte solution may be helpful for mild diarrhea because electrolytes may be lost from the GI tract. With diarrhea, the loss of potassium (K+) could result in hypokalemia. Loss of water and electrolytes can result in hypertonic dehydration, so fluid therapy would be geared to restore normal hemodynamics and fluid osmolality, bringing needed electrolytes back into balance.

Acute diarrhea caused by most common organisms rarely persists for more than 4–5 days. With acute diarrhea, some nutrient intake is generally possible, but it is important to note that the probable etiology of the diarrhea should be determined prior to making decisions about what to feed the child.

The AAP provides the following guidelines for fluid requirements during illness to help prevent dehydration.

Oral fluid recommendations during illness

Estimated Oral Fluid and Electrolyte Requirements by Body Weight
Body Weight
(in pounds)>
Minimum Daily Fluid Requirements
(In Ounces)*
Electrolyte Solution Requirements for Milk Diarrhea (InOunces for 24 Hours)
6-7  10 16
11 15 23
22 25 40 
26 28 44 
33 32 51
40 38 61


The fluoridation of water in many communities has contributed greatly to reduction in dental caries. The Centers for Disease Control and Prevention named water fluoridation as one of the top 10 public health achievements of the 20th century.

The AAP recommends that infants should not receive fluoride supplementation during the first 6 months, whether they are breastfed or formula-fed. After that time, breastfed and formula-fed infants need appropriate fluoride supplementation if local drinking water contains less than 0.3 parts per million (ppm) of fluoride.


As one of the six essential nutrients, water is an important part of a healthy, balanced diet at all ages. Nutrition discussions with parents present a valuable opportunity to emphasize the value of water as a part of their child’s daily diet, as well as the preferred choice for hydration in place of sweetened drinks for toddlers, preschoolers and older children.

American Academy of Pediatrics Committee on Nutrition. Kleinman RE, ed. Pediatric Nutrition Handbook. 6th Edition. © 2009 American Academy of Pediatrics.

Merck Manual. Physical growth: Body composition.

American Academy of Pediatrics. Ages and Stages: Water and Juice.

American Academy of Pediatrics. Health Issues: Treating Vomiting.

Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Food and Nutrition Board, Institute of Medicine, National Academies, 2005.

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