The Sustainable Development Goal drinking water indicators include microbiological safety measures, whereas the Millennium Development Goal indicator ‘improved water’ may be microbiologically unsafe. In rural Vanuatu, we undertook household surveys, child anthropometry, and tested stored drinking water, to investigate relationships between water and undernutrition. Using Escherichia coli most probable number, we categorized results according to Compartment Bag Test drinking water cutoffs: <1/100 mL (safe), 1–10/100 mL (intermediate risk), >10–100/100 mL (high risk), and >100/100 mL (very high risk). Of 201 households, 191 (95%) had microbiologically unsafe drinking water, regardless of ‘improved’ status. We investigated cross-sectional associations between households with microbiologically safer drinking water (≤10 E. coli/100 mL) versus ‘improved water’ and undernutrition among children. Of children under 5, 145 (48.8%, 95% CI: 42.8, 54.8) were stunted and 59 (19.1%, 95% CI: 14.4, 23.8) were underweight. Among households with ‘improved water’, the adjusted prevalence ratio (95% CI) of stunting was 0.61 (0.46, 0.80) and underweight was 0.46 (0.29, 0.73) compared with ‘unimproved water’. However, we found no association between having drinking water with ≤10 E. coli/100 mL at one point in time and undernutrition. Longer-term variations in water quality and unmeasured conditions beyond water may have contributed to these associations.

可持续发展目标饮用水指标包括微生物安全措施，而千年发展目标指标“改善水质”在微生物学上可能是不安全的。在瓦努阿图农村地区，我们进行了家庭调查，儿童人体测量学，并测试了储存的饮用水，以调查水与营养不良之间的关系。使用大肠杆菌最可能的数字，我们根据隔室袋测试饮用水的截止值将结果分类：<1/100毫升（安全），1–10 / 100毫升（中等风险），> 10–100 / 100毫升（高风险）和> 100/100 mL（非常高的风险）。在201户家庭中，无论“改善”状态如何，都有191种微生物（95％）的饮用水在微生物学上不安全。我们调查了微生物安全饮用水（≤10大肠杆菌）的家庭之间的横断面关联/ 100 mL）与“改善水质”和儿童营养不良之间的关系。在5岁以下的儿童中，发育迟缓的儿童有145（48.8％，95％CI：42.8，54.8），体重不足的儿童有59（19.1％，95％CI：14.4，23.8）。在“水质得到改善”的家庭中，与“水质未得到改善”相比，调整后的发育不良患病率（95％CI）为0.61（0.46，0.80），体重不足为0.46（0.29，0.73）。但是，我们发现在某一时间饮用≤10大肠杆菌/ 100 mL的饮用水与营养不良之间没有关联。水质的长期变化和超出水的不可测条件可能促成了这些关联。