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United States Department of Agriculture

Agricultural Research Service

Research Project: USDA NATIONAL NUTRIENT DATABANK FOR FOOD COMPOSITION

Location: Nutrient Data

Title: The mineral content of tap water in United States households

Authors
item Patterson, Kristine
item Pehrsson, Pamela
item Perry, Charles -

Submitted to: Journal of Food Composition and Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 29, 2013
Publication Date: March 29, 2013
Repository URL: http://dx.doi.org/10.1016/j.jfca.2013.03.004
Citation: Patterson, K.K., Pehrsson, P.R., Perry, C.R. 2013. The mineral content of tap water in United States households. Journal of Food Composition and Analysis. Journal of Food Composition and Analysis, 31:46-50.

Interpretive Summary: The consumption of tap water contributes to dietary intake of minerals. The USDA’s Nutrient Data Laboratory (NDL) conducted a study of the mineral content of residential tap water, to generate current data to include in the USDA National Nutrient Database that is available on the internet. Sodium, potassium, calcium, magnesium, iron, copper, manganese, phosphorus, and zinc content of drinking water were determined in a nationally representative sampling. The sampling method identified 144 locations for water collection in winter and spring from home taps. If about one quart of tap water is consumed daily, only four minerals, on average, provide more than 1% of the U.S. Dietary Reference Intake, copper, calcium, magnesium, and sodium. Significant decreases in calcium were observed with chemical water softeners, and between seasonal pickups for Mg and Ca. The amount of sodium in the tap water varied by the region of the country, but collection time, water source and treatment were not found to affect the sodium concentration. No significant differences in overall mineral content between municipal and well water was found. These results, which are a nationally representative dataset of mineral values for drinking water available from home taps, provide valuable additional information for assessment of dietary mineral intake.

Technical Abstract: The composition of tap water contributes to dietary intake of minerals. The USDA’s Nutrient Data Laboratory (NDL) conducted a study of the mineral content of residential tap water, to generate current data for the USDA National Nutrient Database. Sodium, potassium, calcium, magnesium, iron, copper, manganese, phosphorus, and zinc content of drinking water were determined in a nationally representative sampling. The statistically designed sampling method identified 144 locations for water collection in winter and spring from home taps. Assuming a daily consumption of one liter of tap water, only four minerals, on average, provided more than 1% of the US Dietary Reference Intake, copper, calcium, magnesium, and sodium. Significant decreases in calcium were observed with chemical water softeners, and between seasonal pickups for Mg and Ca. The variance of sodium was significantly different among regions (p<0.05) but no differences were observed as a result of collection time, water source or treatment. Based on the weighted mixed model results, there were no significant differences in overall mineral content between municipal and well water. These results, which are a nationally representative dataset of mineral values for drinking water available from home taps, provide valuable additional information for assessment of dietary mineral intake.

Last Modified: 10/20/2014
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