In the US, about 15 million families get their drinking water from private, unregulated wells. Studies show that a significant number of these wells have concentrations of nitrates that exceed federal drinking-water standards. These nitrates are a natural component of plants and nitrate-containing fertilizers that can seep into well water, and don’t pose any toxic risk to humans on their own. But in the body, they can be converted to nitrites, which are potentially hazardous. In infants, they can lead to a condition called methemoglobinemia, a dangerous and often fatal blood disorder that interferes with the circulation of oxygen in the blood.
Babies whose formula is prepared using well water may have a high risk of nitrate poisoning. The AAP recommends that if your family drinks well water, the well should be tested for nitrates. If the well water contains nitrates (above a level of 10 mg/L), it should not be used for infant formula or food preparation. Instead, you should prepare food or formula by using purchased water, public water supplies, or water from deeper wells with minimal nitrate levels.
How often should well water be tested? Tests should be done every three months for at least one year to determine the levels of nitrates. If these tests show safe levels, then a follow-up test once a year is recommended.
Breastfeeding is another important and safe way to nourish your infant, since high levels of nitrates are not passed through breastmilk.