Objective To investigate the level of total hardness in drinking water of Yangzhou in China as well as its change and distribution patterns, and to provide a scientific basis for improving the water quality of Yangzhou.
Methods The drinking water quality data monitored by the centers for disease control and prevention at all levels in Yangzhou during dry and wet seasons in 2008—2022 were collected. The changes in total hardness were compared for different years, counties/districts, water periods, and water sources.
Results A total of 11 402 drinking water samples were collected, with a median total hardness of 146 mg/L and an overall qualified rate of 99.95%. According to the classification of water based on total hardness in China, the proportions of extremely soft water, soft water, medium hard water, hard water, high hard water, and ultra-high hard water were 0.03% (3 samples), 53.10% (6 055 samples), 45.70% (5 211 samples), 1.11% (127 samples), 0.04% (4 samples), and 0.02% (2 samples), respectively. The total hardness varied significantly across different years, counties/districts, water periods, and water sources (P < 0.001).
Conclusion The total hardness of drinking water in Yangzhou is satisfactory, with the majority of water samples classified as soft or medium hard water. However, there are areas requiring improvement, particularly in County A, during the dry season, and in deep well water sources, which require the implementation of appropriate measures to enhance water quality.
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