Rooftop rainwater harvesting systems and blue-green infrastructure are becoming important resilience alternatives for urban climate adaptation. This study sheds light on the largely unreported physicochemical and microbiological quality of private roof-harvested rainwater (RHRW). We aimed to identify the physicochemical and microbiological characteristics of RHRW, explore potential correlations between them and assess probable health risks associated with recreational interactions of children with the water. RHRW was collected from cisterns and ponds located in an inner courtyard in Hanover, Germany. Physicochemical parameters were measured on site and samples were collected once a month in two campaigns in 2020 and 2021. Escherichia coli concentrations ranged from 1 × 10° to 24.1 × 10² MPN/100 mL, Enterococci from 1 × 10° to 19.7 × 10² MPN/100 mL, Salmonella from 1 × 10² to 39 × 10³ CFU/100 mL and Pseudomonas aeruginosa from 1 × 10° to 3 × 10³ MPN/100 mL. Correlation analysis indicated potential relationships between bacteria, oxygen, and water temperature. The results of the health risk assessment indicated a potential risk of gastrointestinal illnesses due to exposure to Enterococci and Salmonella spp. present in the cisterns and ponds, highlighting the need for appropriate regulations and guidelines for RHRW aimed for non-potable uses. Blue-green infrastructure, when effectively managed and maintained, can offer benefits both by enhancing urban climate resilience and promoting citizens well-being.

屋顶雨水收集系统和蓝绿基础设施正在成为城市气候适应的重要弹性替代方案。这项研究揭示了大部分未报告的私人屋顶收集雨水（RHRW）的物理化学和微生物质量。我们的目的是确定 RHRW 的物理化学和微生物学特征，探索它们之间的潜在相关性，并评估与儿童与水的娱乐互动相关的可能健康风险。RHRW 是从位于德国汉诺威内部庭院的水箱和池塘中收集的。2020年和2021年的两次活动中，现场测量了理化参数，每月采集一次样品。大肠杆菌浓度范围为1 × 10°至24.1 × 10 ² MPN/100 mL，肠球菌浓度范围为1 × 10°至19.7 × 10 ² MPN/100 mL，沙门氏菌为 1 × 10 ²至 39 × 10 ³  CFU/100 mL，铜绿假单胞菌为 1 × 10° 至 3 × 10 ³ MPN/100 mL。相关分析表明细菌、氧气和水温之间的潜在关系。健康风险评估结果显示，由于接触肠球菌和沙门氏菌，存在患胃肠道疾病的潜在风险。存在于蓄水池和池塘中，强调需要针对非饮用水用途制定适当的 RHRW 法规和指南。蓝绿基础设施如果得到有效管理和维护，可以通过增强城市气候适应能力和促进公民福祉来带来好处。