Differences and variations of drinking water quality between the northern and southern regions of a tropical island and the indicators influenced by meteorological factors

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Climate change poses a considerable threat to humanity. This study aims to explore the effects of meteorological factors on drinking water quality in urban and rural areas in the tropics. Drinking water was assessed by performing correlation and logistic regression analyses on South China from 2021 to 2023. Results showed that fluorine and chemical oxygen demand were low in the north countryside. The total bacterial count (TBC), sulfate, chloride, manganese, total dissolved solids, arsenic, ferrum, nitrate, total hardness, pH value, and turbidity in the north were higher than those in the rural south. Terminal tap water from northern rivers and southern lakes was significantly affected by meteorological factors (p < 0.05). In general, the microorganisms increased with temperature (r = 0.156–0.737) and trichloromethane (r > 0.633, odds ratio (OR) > 1). Arsenic increased with temperature in the north rural areas (OR > 1). High levels of NO₃⁻ corresponded to increased frequency of extreme rainstorms. Furthermore, trichloromethane, aluminum, nitrate, and TBC were most susceptible to extreme meteorological factors in the tropics. Fluorine from different sources showed inconsistency. Chemical types and dosing or treatment adjustments in water treatment processes may help address deteriorated water quality during extreme weather events.

• High temperatures increase bacteria in terminal tap water in tropical cities and countryside.

• Trichloromethane, aluminum, nitrate, and microorganisms were susceptible to extreme meteorological factors.

• Decrease of ClO₃⁻ with solar radiation probably reveals the advantage of ClO₂ disinfection in the tropical countryside.

• Arsenic increases in dry seasons in northern rural regions with high temperatures.