Trichomonas gallinae, a well-documented protozoan parasite of avian hosts, has been implicated in major passerine mortality events recently and historically throughout the literature. It has been suggested that bird baths and artificial water sources could serve as a source of infection for naive birds; however, trichomonad persistence in water is not well understood. We measured the persistence of T. gallinae isolates from two avian hosts in distilled water and distilled water with the addition of organic material. We inoculated plastic containers in a laboratory setting with 1 × 10⁶ trichomonads and then sampled 500 μl from each container at various time points postinoculation (0–20 hr). The 500-μl aliquots were inoculated into flasks with 5 ml of modified Diamond media at each time point. Flasks were incubated at 37 C and examined by light microscopy for five consecutive days for the characteristic movements of live trichomonads. The maximum persistence was 16 hr with a Cooper’s hawk (Accipiter cooperii) isolate in the organic material treatment, far longer than the 1 hr persistence previously reported. We show that T. gallinae isolates are capable of persisting for long periods of time in water, illustrating that bird baths may be validated as a potential source of transmission in epidemics.