Objectives  To systematically analyze the relationship between urban and rural drinking water quality and the incidence of water-borne infectious diseases in Yubei District, Chongqing, from 2016 to 2024. This study aims to provide a scientific basis for improving water quality, reducing disease incidence, assisting government departments in formulating public health strategies, and strengthening health security barriers.

Methods Drinking water samples from urban and rural areas of Yubei District were monitored from 2016 to 2024. Concurrent data on the incidence of water-borne infectious diseases were collected via the China Information System for Disease Control and Prevention (CISDCP) Infectious Disease Surveillance Reporting System. Descriptive analysis was performed using SPSS 26.0 software. Trend analysis was conducted using Joinpoint regression. Spearman rank correlation and linear regression were employed to analyze the correlation between drinking water quality parameters and water-borne infectious diseases and to quantify the impact.

Results From 2016 to 2024,1,540 drinking water samples were collected in Yubei District, of which 1,130 were qualified, yielding an overall qualification rate of 73.38%.The qualified rate of water quality increased from 50.59% in 2016 to 96.30% in 2024, with a significant upward trend from 2016 to 2021 (APC=15.00, P<0.05). The qualification rate for microbiological indicators improved from 52.94% to 100%. A total of 35,594 cases of water-borne infectious diseases were reported during the same period, predominantly infectious diarrheal diseases. The incidence of Hepatitis A showed a significant decreasing trend from 2016 to 2020 (APC=−11.76, P< 0.05), followed by a non-significant slow increase from 2020 to 2024; The incidence rate of hepatitis E from 2016 to 2024 showed an upward fluctuating trend (APC=−6.42, P<0.05).; The incidence of Bacillary Dysentery showed a significant decreasing trend (APC=−28.97, P< 0.05). Bacillary Dysentery and infectious diarrheal diseases were significantly negatively correlated with both the overall water qualification rate and the microbiological qualification rate (P<0.05). Linear regression analysis demonstrated that the incidence rates of these diseases decreased significantly as the water sample qualification rate increased (P<0.05) .

Conclusion  The sanitary status of urban and rural drinking water in Yubei District, Chongqing, significantly improved from 2016 to 2024. Water quality improvement had a marked effect on controlling Bacillary Dysentery and infectious diarrheal diseases. This study confirms that the "monitoring supervision" multi-departmental coordination mechanism implemented in Yubei District after 2019, along with the standardized renovation of water treatment plants, were key drivers of water quality enhancement and the subsequent decline in disease incidence. It is recommended to continuously strengthen the monitoring of microbiological indicators to provide technical support for public health policy formulation.