The question of giving water, especially purified types like distilled water, often arises when feeding newborns. The medical consensus is that plain water, regardless of its source or purity, is not necessary and may even be harmful for infants typically under six months of age. This recommendation stems from the newborn’s unique nutritional needs and the immaturity of their internal systems. Understanding why water is restricted for babies in this age range is crucial for safe feeding practices.
Why Plain Water is Unsafe for Newborns
The primary reason to withhold plain water from young infants is that their bodies are not yet equipped to handle the fluid load. A newborn’s kidneys, while functional, are significantly less developed than an adult’s and have a limited capacity to process excess water and excrete it efficiently. This diminished capacity means that introducing extra water can quickly overwhelm the system, potentially leading to a dangerous electrolyte imbalance.
Breast milk and properly prepared infant formula are already composed of approximately 85% to 87% water, providing all the necessary hydration. Giving plain water fills the baby’s small stomach without offering any calories or nutrients. Since a one-month-old’s stomach is only about the size of an egg, water displaces the nutrient-dense milk or formula needed for growth. This caloric dilution can impede proper weight gain.
The physiological risk involves the dilution of the blood’s sodium concentration, a condition known as hyponatremia, or water intoxication. When excess water enters the bloodstream, it lowers the sodium level below the normal threshold of 135 milliequivalents per liter. Because the baby’s kidneys cannot adequately filter this load, the resulting low sodium causes cells throughout the body to swell, which is particularly hazardous for the developing brain.
The Specifics of Distilled Water Composition
Distilled water is produced by boiling water into steam and then condensing the steam back into a liquid. This distillation method removes over 99.9% of dissolved solids, minerals, and impurities, including bacteria, heavy metals, and chemicals. The result is nearly pure water.
While distilled water is free of contaminants, it contains zero electrolytes or minerals. This lack of minerals, such as sodium and potassium, makes the water hypotonic, meaning it has a lower concentration of solutes than the body’s fluids. Giving distilled water to an infant carries the same risk of hyponatremia as any other plain water because it still dilutes the body’s existing sodium levels.
The absence of minerals, including fluoride, is a double-edged sword when considering formula preparation. Some parents choose distilled water to avoid the potential risk of mild dental fluorosis, which can appear as faint white streaks on the teeth from excessive fluoride intake. However, this choice also means the baby misses out on the beneficial effects of fluoride in preventing tooth decay, which is why alternating with fluoridated water is often suggested.
Safe Water Options for Formula Preparation
When using powdered or concentrated liquid formula, water is necessary, and its source must be carefully considered for safety. For most healthy infants, tap water that is consistently monitored for contaminants by a local public water system is generally acceptable for mixing formula. However, if a family uses well water, it must be tested regularly, as it can contain harmful contaminants like nitrates or pathogens that boiling cannot remove.
For infants under two months of age, those born prematurely, or those with a weakened immune system, boiling the water is a necessary safety step. Water should be brought to a rolling boil for one minute to kill any potential microbes.
Boiling Instructions
It is crucial to allow the boiled water to cool to a temperature no lower than 158°F (70°C) before mixing it with the powder. This heat is necessary to inactivate bacteria, such as Cronobacter, that may be present in the powdered formula itself.
Bottled water is another option, but parents should select purified, deionized, or demineralized varieties, often marketed as “nursery water,” which are low in mineral content. It is important to avoid bottled water labeled as “mineral water” due to its high concentration of dissolved solids, which can strain a baby’s developing kidneys. Ready-to-feed formula is the safest option in emergency situations or when the water source is questionable, as it requires no added water.
Recognizing Symptoms of Water Intoxication
Water intoxication occurs when the sodium level in the bloodstream falls too low. This serious condition requires immediate attention because it can lead to swelling of the brain tissue. Caregivers should be vigilant for acute symptoms if an infant has received excessive plain water or overly diluted formula.
The early signs of water intoxication include unusual fussiness, irritability, and lethargy. More severe symptoms indicating a dangerous drop in sodium levels include a low body temperature (hypothermia) and puffiness in the face. In the most serious cases, the infant may experience seizures, vomiting, poor coordination, or a coma, which necessitates calling emergency medical services immediately.