This paper provides a description of the dose monitoring approaches used by ultraviolet (UV) reactors designed to treat drinking water and addresses issues including: comparing the different monitoring methods; the optimum position for UV intensity sensors relative to the UV lamps; the impact of differing UV intensity sensor properties; and, safety factors required to account for uncertainty in dose monitoring. Approaches used by UV reactors to monitor dose delivery fall into three categories: UV intensity setpoint approaches; UV intensity / UV transmittance setpoint approaches; and, calculated dose approaches. Includes 8 references, tables, figures.