A water tank is provided for communicating with a cleaning system on a base station body of a base station and outside of the base station. The water tank includes a clean water cavity configured to hold clean water, a clean water input channel configured to be communicated with the clean water cavity and an external water source outside the base station, a clean water output channel configured to be communicated with the clean water cavity and the cleaning system on the base station body, a sewage cavity configured to hold sewage, a sewage input channel configured to be communicated with the cleaning system on the base station body and the sewage cavity, and a sewage output channel configured to be communicated with the sewage cavity and outside of the base station.