Water purifying drink containers include a liquid container, a cap assembly removably coupled to the liquid container, and a purification assembly that emits ultraviolet (UV) light in the germicidal spectrum to purify a volume of drink liquid held in the liquid container. In some embodiments, the purification assembly includes a UV bulb positioned within a recess of the cap assembly facing the internal compartment of the liquid container. In some embodiments, the UV bulb further emits light in the visible spectrum and the drink container includes an indicator that becomes illuminated with visible light to indicate to a user when the UV bulb is emitting UV light.