Distilled Water Assessment
Some families in Minnesota use distilled or purified bottled water for mixing infant formula if they are concerned about contaminants in their well water or municipal tap water. Since babies consume more water in relation to their body weight than any other age segment of the population, it is important to know what contaminants may be in the water used to mix their formula. Prior to this study, little was known about contaminants that might occur in bottled distilled water. Staff in the Minnesota Department of Health (MDH) conducted this study to assess what contaminants might occur in distilled water, and what the level was of each of the contaminants present.
Containers of distilled or purified drinking water were purchased at twelve different locations around the Twin Cities. Some of the products were simply labeled as distilled water; others were labeled as distilled or purified water intended specifically for infant formula use. Some of the products were purified by distillation, others by reverse osmosis. The water samples were analyzed at the MDH Public Health Laboratory for various metal and organic contaminants. We did not expect to find high levels of contaminants in the purified bottled water because purification processes are very effective at removing contaminants. However, we also did not expect to find completely contaminant free water, as some contaminants can persist after treatment and some can enter the water after treatment.
Most of the compounds we tested for were not found in any of the samples. The few compounds that were detected were mostly volatile organic compounds (VOCs) or chlorinated solvents, and these were detected at levels well below health guidelines. VOCs are contaminants that can move easily from water to air, so it may be that the treatment processes for water were less effective at removing these compounds. There was little evidence of contaminants entering the water from the plastic bottles.
This is a limited study with a small sample size, as only twelve samples were analyzed. However, the results show that when distilled water contains contaminants, these contaminants occur at levels far below current MDH and federal health guidance values for drinking water. Based on this study, MDH is able to reassure parents with concerns about the quality of their tap water that water labeled as distilled, purified using distillation, or purified using reverse osmosis can be used to prepare their infant’s formula.