目的评定集中式供水中pH测定不确定度。方法根据JJF 1059.1-2012《测量不确定度评定与表示》及GB/T5750.4-2006《生活饮用水卫生标准检验方法》中生活饮用水pH测定方法,建立不确定度的数学模型,分析不确定度来源,量化不确定度分量,评定集中式供水中pH测定的不确定度。结果不确定度评定结果为pH=7.04±0.04,k=2(95%置信度)。结论 pH计的精密度是集中式供水中pH测定不确定度的主要来源,其次是pH标准缓冲液。 Objective To assess the uncertainty of pH determination in a centralized water supply. Methods According to JJF 1059.1-2012 “Evaluation and Expression of Uncertainty in Measurement” and pH measurement method of drinking water in GB / T5750.4-2006 “Drinking Water Hygiene Standard Test Method”, a mathematical model of uncertainty is established. Determine the source of the degree of uncertainty, quantify the uncertainty component, and assess the uncertainty of the pH measurement in a centralized water supply. Results The uncertainty was evaluated as pH = 7.04 ± 0.04, k = 2 (95% confidence). Conclusion The precision of the pH meter is the main source of uncertainty in the pH measurement of the centralized water supply, followed by the pH standard buffer.