Prospects for a multi-TeV gamma-ray sky survey with the LHAASO water Cherenkov detector array *Supported by National Natural Science Foundation of China (11761141001, 11635011, 11873005). The LHAASO project is supported by the National Key R & D Program of China (2018YFA0404200), the Chinese Academy of Sciences, the Key Laboratory of Particle Astrophysics, IHEP, CAS. (June 2020)