Western Water Infrastructure Act of 2021 This bill reauthorizes and modifies certain Bureau of Reclamation programs related to water storage, eligible desalination projects, and reclamation and reuse of wastewater and groundwater in western states. Also, Reclamation must (1) develop a sediment management plan for their reservoirs upon request by project beneficiaries; (2) perform enhanced inspections for aging infrastructure to ensure their safe operation upon request by the owner or operator; and (3) carry out activities to reduce or eliminate certain rehabilitation, reconstruction, and replacement needs of Reclamation.