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Is the default of 2 liters for daily per-capita water consumption appropriate? A nationwide survey reveals water intake in Japan

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Title: Is the default of 2 liters for daily per-capita water consumption appropriate? A nationwide survey reveals water intake in Japan
Authors: Ohno, Koichi Browse this author
Asami, Mari Browse this author
Matsui, Yoshihiko Browse this author →KAKEN DB
Keywords: drinking water
community water
direct and indirect intake
exposure assessment
Issue Date: 1-Aug-2018
Publisher: IWA Publishing
Journal Title: Journal of Water and Health
Volume: 16
Issue: 4
Start Page: 562
End Page: 573
Publisher DOI: 10.2166/wh.2018.281
PMID: 30067239
Abstract: Two liters per day is generally applied as the default drinking-water intake rate for risk assessments, although evidence supporting this value is insufficient. This study aimed to reveal actual water intakes from tap water and other types of drinks, and to explore the relationships between these intakes. For this purpose, we conducted a nationwide Internet questionnaire survey. Tap water intake negatively correlated with bottled water and soft drink intakes, suggesting a mutually complementary relationship. We propose an index, potential Tap Water Intake (pTWI), calculated by adding soft drinks and bottled water to tap water intake. Mean per-capita tap water intake across the entire Japanese population was estimated at 1.28 L/d, whereas mean pTWI was estimated at 1.65 L/d. Two liters per day corresponds to the 88th percentile of tap water intake and to the 76th percentile of pTWI, and covers the intake of the majority of population in Japan. This rate should continue being used for the default in the Japanese population, but the rate to cover the tap water intake of almost the entire population would be higher: it was > 2.5 L/d.
Rights: ©IWA Publishing 2018. The definitive peer-reviewed and edited version of this article is published in Journal of water and health 16(4),562-573,2018, and is available at
Type: article
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 松井 佳彦

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