STUDY: Almost One Third of U.S. Adults are Not Properly Hydrated Due to Racial, Ethnic, and Socioeconomic Disparities

A study from the Harvard T. H. Chan School of Public Health found that racial/ethnic disparities in intake of tap water may be partly responsible for racial/ethnic disparities in hydration among U.S. adults.

The consumption of safe drinking water is essential for adequate hydration and physiological functioning. Those who are mildly or inadequately hydrated may not find themselves needing urgent medical attention, but may be at greater risk for other medical conditions, such as fatigue or impaired cognitive functions. Race, ethnicity, and socioeconomic status have been found to play a role in water intake, with non-Hispanic Black and Hispanic adults consuming less than non-Hispanic White adults.

“We knew there were disparities in hydration status among kids in the U.S., and wanted to see if a similar pattern would emerge among adults. Additionally, the Flint, MI water crisis and other research led us to want to investigate the idea that perhaps disparities in tap water intake may play a role in the patterns we would find in adult hydration status.”

In the study, Brooks and PRC researchers analyzed data collected over a four-year period from more than 8,000 U.S. adults (ages 20-74) participating in the National Health and Nutrition Examination Survey. To assess hydration status, the researchers used a test to measure how concentrated a person’s urine is, known as “urine osmolality.” They examined how an individual’s hydration status was affected by the consumption of tap water versus other beverages. In addition, the researchers looked at intake of tap water in parallel with race, ethnicity, and income to determine if differences in tap water consumption could account for poor hydration status outcomes among Non-Hispanic Black, Hispanic, and low-income adults.Boy drinking bottled water outside

Major findings included that—when compared to Non-Hispanic white adults—Non-Hispanic Blacks and Hispanics were 40% more likely to be inadequately hydrated. Further, lower-income individuals were 20% more likely to be inadequately hydrated. The researchers also found that tap water intake partially accounted for inadequate hydration status with respect to race, ethnicity, and income. In conclusion, the results indicated that tap water could be a key player when it comes to improving hydration status among at-risk groups.

Media Coverage

Significant racial, ethnic, income disparities in hydration found among U.S. adults
– Harvard T. H. Chan School of Public Health

Access may explain some social disparities in U.S. water intake
-Reuters U.K.


Lead author Carolyn Brooks, Dr. Anisha Patel, and Kelley Dearing-Smith discuss a massive public health problem which is rarely mentioned and probably underestimated — unequal access to water in the United States –in this podcast with the American Journal of Public Health hosted by Alfredo Morabia. Listen Now

Brooks CJ, Gortmaker SL, Long MW, Cradock AL, Kenney EL. Racial/Ethnic and Socioeconomic Disparities in Hydration Status Among US Adults and the Role of Tap Water and Other Beverage Intake. American Journal of Public Health. 2017. e-View Ahead of Print.