Water hardness and digestive diseases: a large-scale population-based prospective cohort study

Qida He; Mengtong Sun; Jingting Huang; Qi Wang; Gary Adamkiewicz; Yueping Shen; Linyan Li

doi:10.1097/JS9.0000000000003506

Water hardness and digestive diseases: a large-scale population-based prospective cohort study

Qida He (Co-first Author), Mengtong Sun (Co-first Author), Jingting Huang, Qi Wang, Gary Adamkiewicz, Yueping Shen^*, Linyan Li^*

^*Corresponding author for this work

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

4 Downloads (CityUHK Scholars)

Abstract

Background: Water hardness, which refers to the level of dissolved calcium and magnesium salts, is of significant public health concern due to its potential impact on health. The association between water hardness and digestive diseases remains underexplored, with limited evidence from small-scale clinical studies. Given the rising prevalence of digestive disorders worldwide, large-scale cohort studies are needed to address this gap in the literature.

Methods: This study is to explore the link between domestic water hardness and the risk of digestive disorders, leveraging data from 356 000 individuals within a large prospective cohort study. Water hardness was assessed through regional data on CaCO₃ concentrations, categorized into soft, moderately hard, hard, and very hard water based on United States Geological Survey (USGS) standards. The primary outcome of interest was incident cases of a composite of digestive system diseases. Cox proportional hazard regression models were employed to evaluate the association between water hardness and the risk of 16 digestive diseases.

Results: Our study revealed a nonlinear association between water hardness and digestive health. Higher levels of water hardness (>180 mg/L CaCO₃) were inversely associated with the risk of several digestive conditions, including dyspepsia, constipation, and gallbladder disease, when compared to exposure to soft water. Conversely, exposure to moderately hard water (60–120 mg/L CaCO₃) was linked to increased risks of conditions such as peptic ulcer and gastroesophageal reflux disease.

Conclusions: This study provides important insights into the epidemiological associations between drinking water hardness and various digestive system diseases, suggesting that water quality may have potential impacts on public health.

Original language	English
Pages (from-to)	922-934
Number of pages	13
Journal	International Journal of Surgery
Volume	112
Issue number	1
Online published	10 Sept 2025
DOIs	https://doi.org/10.1097/JS9.0000000000003506
Publication status	Published - Jan 2026

Funding

This work was supported by the Research Grants Council of the Hong Kong Special Administrative Region, China (Grant number CityU 21607223; Grant number C6003- 22Y) and the City University of Hong Kong start-up grant (Project number 9610576). Open Access made possible with partial support from the Open Access Publishing Fund of the City University of Hong Kong.

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 3 Good Health and Well-being
SDG 6 Clean Water and Sanitation

Research Keywords

calcium
drinking water
inflammatory bowel disease
magnesium
non-alcoholic fatty liver disease
UK Biobank

Publisher's Copyright Statement

This full text is made available under CC-BY-NC-ND 4.0. https://creativecommons.org/licenses/by-nc-nd/4.0/

RGC Funding Information

RGC-funded

Access Output

10.1097/JS9.0000000000003506

364645827.pdfFinal Published version, 2.71 MBLicence: CC BY-NC-ND

Other Access Options

Check CityUHK Library

Permanent Link

Right click to copy link

ECS: Advancing Exposure Assessment of the Built Environment and Studying Its Associations with Various Health Outcomes
LI, L. (Principal Investigator / Project Coordinator)
1/01/24 → …
Project: Research
YCRG-ExtU-Lead: Toward 2060 Carbon Neutrality: Life-cycle Planning and Design of Photovoltaic Integrated Green Roof (PVIGR) Systems for Hong Kong and the Greater Bay Area
Wang, Z. (Main Project Coordinator [External]) & LI, L. (Principal Investigator / Project Coordinator)
15/06/23 → …
Project: Research

Cite this

@article{22c67b17ff5244129ed68396e011a3c3,

title = "Water hardness and digestive diseases: a large-scale population-based prospective cohort study",

abstract = "Background: Water hardness, which refers to the level of dissolved calcium and magnesium salts, is of significant public health concern due to its potential impact on health. The association between water hardness and digestive diseases remains underexplored, with limited evidence from small-scale clinical studies. Given the rising prevalence of digestive disorders worldwide, large-scale cohort studies are needed to address this gap in the literature.Methods: This study is to explore the link between domestic water hardness and the risk of digestive disorders, leveraging data from 356 000 individuals within a large prospective cohort study. Water hardness was assessed through regional data on CaCO3 concentrations, categorized into soft, moderately hard, hard, and very hard water based on United States Geological Survey (USGS) standards. The primary outcome of interest was incident cases of a composite of digestive system diseases. Cox proportional hazard regression models were employed to evaluate the association between water hardness and the risk of 16 digestive diseases.Results: Our study revealed a nonlinear association between water hardness and digestive health. Higher levels of water hardness (>180 mg/L CaCO3) were inversely associated with the risk of several digestive conditions, including dyspepsia, constipation, and gallbladder disease, when compared to exposure to soft water. Conversely, exposure to moderately hard water (60–120 mg/L CaCO3) was linked to increased risks of conditions such as peptic ulcer and gastroesophageal reflux disease.Conclusions: This study provides important insights into the epidemiological associations between drinking water hardness and various digestive system diseases, suggesting that water quality may have potential impacts on public health.Copyright {\textcopyright} 2025 The Author(s).",

keywords = "calcium, drinking water, inflammatory bowel disease, magnesium, non-alcoholic fatty liver disease, UK Biobank",

author = "Qida He and Mengtong Sun and Jingting Huang and Qi Wang and Gary Adamkiewicz and Yueping Shen and Linyan Li",

note = "Copyright {\textcopyright} 2025 The Author(s). Published by Wolters Kluwer Health, Inc.",

year = "2026",

month = jan,

doi = "10.1097/JS9.0000000000003506",

language = "English",

volume = "112",

pages = "922--934",

journal = "International Journal of Surgery",

issn = "1743-9191",

publisher = "Wolters Kluwer Health Inc",

number = "1",

}

TY - JOUR

T1 - Water hardness and digestive diseases

T2 - a large-scale population-based prospective cohort study

AU - He, Qida

AU - Sun, Mengtong

AU - Huang, Jingting

AU - Wang, Qi

AU - Adamkiewicz, Gary

AU - Shen, Yueping

AU - Li, Linyan

PY - 2026/1

Y1 - 2026/1

N2 - Background: Water hardness, which refers to the level of dissolved calcium and magnesium salts, is of significant public health concern due to its potential impact on health. The association between water hardness and digestive diseases remains underexplored, with limited evidence from small-scale clinical studies. Given the rising prevalence of digestive disorders worldwide, large-scale cohort studies are needed to address this gap in the literature.Methods: This study is to explore the link between domestic water hardness and the risk of digestive disorders, leveraging data from 356 000 individuals within a large prospective cohort study. Water hardness was assessed through regional data on CaCO3 concentrations, categorized into soft, moderately hard, hard, and very hard water based on United States Geological Survey (USGS) standards. The primary outcome of interest was incident cases of a composite of digestive system diseases. Cox proportional hazard regression models were employed to evaluate the association between water hardness and the risk of 16 digestive diseases.Results: Our study revealed a nonlinear association between water hardness and digestive health. Higher levels of water hardness (>180 mg/L CaCO3) were inversely associated with the risk of several digestive conditions, including dyspepsia, constipation, and gallbladder disease, when compared to exposure to soft water. Conversely, exposure to moderately hard water (60–120 mg/L CaCO3) was linked to increased risks of conditions such as peptic ulcer and gastroesophageal reflux disease.Conclusions: This study provides important insights into the epidemiological associations between drinking water hardness and various digestive system diseases, suggesting that water quality may have potential impacts on public health.Copyright © 2025 The Author(s).

AB - Background: Water hardness, which refers to the level of dissolved calcium and magnesium salts, is of significant public health concern due to its potential impact on health. The association between water hardness and digestive diseases remains underexplored, with limited evidence from small-scale clinical studies. Given the rising prevalence of digestive disorders worldwide, large-scale cohort studies are needed to address this gap in the literature.Methods: This study is to explore the link between domestic water hardness and the risk of digestive disorders, leveraging data from 356 000 individuals within a large prospective cohort study. Water hardness was assessed through regional data on CaCO3 concentrations, categorized into soft, moderately hard, hard, and very hard water based on United States Geological Survey (USGS) standards. The primary outcome of interest was incident cases of a composite of digestive system diseases. Cox proportional hazard regression models were employed to evaluate the association between water hardness and the risk of 16 digestive diseases.Results: Our study revealed a nonlinear association between water hardness and digestive health. Higher levels of water hardness (>180 mg/L CaCO3) were inversely associated with the risk of several digestive conditions, including dyspepsia, constipation, and gallbladder disease, when compared to exposure to soft water. Conversely, exposure to moderately hard water (60–120 mg/L CaCO3) was linked to increased risks of conditions such as peptic ulcer and gastroesophageal reflux disease.Conclusions: This study provides important insights into the epidemiological associations between drinking water hardness and various digestive system diseases, suggesting that water quality may have potential impacts on public health.Copyright © 2025 The Author(s).

KW - calcium

KW - drinking water

KW - inflammatory bowel disease

KW - magnesium

KW - non-alcoholic fatty liver disease

KW - UK Biobank

U2 - 10.1097/JS9.0000000000003506

DO - 10.1097/JS9.0000000000003506

M3 - RGC 21 - Publication in refereed journal

C2 - 40928362

SN - 1743-9191

VL - 112

SP - 922

EP - 934

JO - International Journal of Surgery

JF - International Journal of Surgery

IS - 1

ER -

Water hardness and digestive diseases: a large-scale population-based prospective cohort study

Abstract

Funding

UN SDGs

Research Keywords

Publisher's Copyright Statement

RGC Funding Information

Access Output

Other Access Options

Permanent Link

Fingerprint

Projects

ECS: Advancing Exposure Assessment of the Built Environment and Studying Its Associations with Various Health Outcomes

YCRG-ExtU-Lead: Toward 2060 Carbon Neutrality: Life-cycle Planning and Design of Photovoltaic Integrated Green Roof (PVIGR) Systems for Hong Kong and the Greater Bay Area

Cite this