Acute oak decline (AOD) is a decline disease affecting oak species native to the UK (Quercus robur and Q. petraea). Part of the wider decline complex, AOD causes tree health decline, causing mortality in as little as five years. Of the four symptoms expressed by AOD-symptomatic trees, the most obvious are black weeping lesions on the stem. The cause of these lesions has been linked to two bacteria, Brenneria goodwinii and Gibbsiella quercinecans, however there is no knowledge on the ecological and environmental reservoirs of these phytopathogens. Rainwater and forest soils are common reservoirs of plant pathogens in a forest environment. Therefore, the aim of this study was to investigate the survival rates of B. goodwinii and G. quercinecans in rainwater and forest soil using a combination of agar-based colony counts and quantitative PCR (qPCR) detection methods. Brenneria goodwinii lost viability in both soil and rainwater at the time of inoculation. Gibbsiella quercinecans, however, could be isolated from rainwater for the entire duration of the experiment (84 days) and was isolated from forest soil up to day 28 of the experiment. These results demonstrate that G. quercinecans has the capacity to survive in environmental forest reservoirs outside of the tree host. qPCR analysis revealed that detection of the G. quercinecans GyrB gene declined in a similar trend to the culture-based study in forest soil. Detection of the B. goodwinii GyrB gene, however, was present up to day 28 of the soil survival experiment. Although further study would be required to understand this, B. goodwinii appears to have a limited ability to persist outside of the host, potentially in a viable but non-culturable (VBNC) state. These data provide evidence that B. goodwinii is an endosymbiont of oak trees, whereas the ability of G. quercinecans to remain viable in soil and rainwater biomes suggests a broad ecological distribution. These data advance understanding of the potential epidemiology of AOD-associated bacteria and their ecological reservoirs, thus increasing the overall knowledge of the pathology of AOD, which could aid in the development of future management strategies.