Faucet water includes both municipal tap water and private well water, each having different safety considerations. Pediatric guidance is clear that infants under six months old should not consume plain water, whether from the faucet or bottled, as their bodies are not yet prepared to process it safely. The primary sources of hydration and nutrition for a baby during this early developmental period must be breast milk or properly prepared infant formula. For older babies, even when water is introduced, its safety for drinking or mixing formula depends heavily on local water quality and how it is prepared.
Age Guidelines for Water Introduction
Infants receive all the necessary hydration from breast milk, which is about 87% water, or from formula, making plain water intake unnecessary for the first half-year of life. Small amounts of water can be introduced around six months of age, aligning with when babies typically begin eating solid foods.
Water introduced at six months is more for practice and developing cup-drinking skills than for hydration, as breast milk or formula remains the main source of fluid and calories. Even after six months, water intake should be limited, with experts suggesting keeping it to a maximum of two to four ounces per day to prevent the baby from feeling full and displacing nutrient intake. Water intake may become a more regular part of the diet closer to 12 months, when reliance on formula or breast milk naturally decreases.
Why Infants Cannot Drink Plain Tap Water
The physiological reason for avoiding plain water in infants under six months relates to their developing organ systems and small stomach capacity. A baby’s kidneys are immature and cannot efficiently process excess water or the minerals found in tap water. This limited renal capacity makes it difficult to regulate the delicate balance of electrolytes and fluid in the body.
Introducing plain water can lead to a serious, though rare, condition called water intoxication, or hyponatremia. Hyponatremia occurs when the sodium levels in the bloodstream become diluted by the excess water. This dilution can cause cells to swell, particularly in the brain, leading to symptoms like irritability, low body temperature, and potentially seizures or brain damage. Furthermore, water can quickly fill a baby’s small stomach without providing nutritional value, interfering with the intake of nutrient-dense breast milk or formula.
Safety Considerations for Tap Water Use
Tap water is routinely used for mixing powdered or concentrated infant formula, which requires specific safety protocols to ensure the mixture is safe for consumption. If there are concerns about the tap water’s microbial safety, such as during a boil water advisory or if the baby is under three months old or immunocompromised, the water should be sterilized. This involves bringing cold tap water to a rolling boil for a full minute, then letting it cool completely before using it to prepare the formula.
Boiling water kills any potential bacteria or other pathogens that may be present. It is important to cool the water to body temperature before mixing the formula, as using water that is too hot can destroy some of the nutrients in the formula powder. Caregivers should use cold water from the tap for boiling, as hot water may contain higher concentrations of dissolved metals like lead from the plumbing.
Addressing Specific Contaminants
Boiling water is effective against biological contaminants but does not remove chemical contaminants; in fact, it can concentrate substances like lead and nitrates. Lead exposure is a significant concern, especially in homes with older plumbing, as it can damage a child’s developing brain and nervous system. Since infants consume a large amount of water relative to their body size, they are particularly vulnerable, and the Environmental Protection Agency has set a maximum contaminant level goal of zero for lead.
Nitrates, often found in well water due to fertilizer runoff, pose a serious risk to infants under six months. High nitrate levels can lead to methemoglobinemia, or “blue baby syndrome,” a condition that impairs the blood’s ability to carry oxygen. The federal limit for nitrate is 10 parts per million (mg/L), established to prevent this condition, though some research suggests harm may occur at even lower levels.
Another consideration is fluoride, which is added to many public water supplies for dental health. However, it can cause dental fluorosis, characterized by white spots on teeth, if overconsumed by formula-fed babies.