COVID-19 outbreak first reported in Wuhan has been officially declared as a global pandemic. Considering the fecal shedding of SARS-CoV-2 has been proven by the viral strains isolated from COVID-19 patient’s stool specimens, it proposed the possibility that contaminated wastewater and fomites might involve in the disease transmission in outbreak cities. In this study, we collected the wastewater samples collected from COVID-19 designated hospitals, Fangcang shelter hospitals, quarantine spots and wastewater treatment plants in Wuhan, China, and performed RT-qPCR and droplet digital PCR (ddPCR) for the detection of SARS-CoV-2. Although high concentration of residual chlorine for disinfection of SARS-CoV-2 is persisted, low level SARS-CoV-2 RNA can be detected by qPCR and droplet digital PCR (ddPCR) in the wastewater samples during the COVID-19 outbreak. This preliminary data firstly described in China implies the potential transmission risk of SARS-CoV-2 through medical wastewater in the cities during the COVID-19 outbreak, which calls particular attention for the surveillance and efficient disinfection of wastewater from COVID-19 related facilities.