Observed climate trends in New Zealand are consistent with projected effects of global climate change. The summer of 2017-2018 was the hottest on record. There have been several severe flood events in recent years, leading to both short term and long term impacts. A major outbreak of campylobacter in Havelock North was linked to contamination of a local water supply following heavy rainfall. Resilience to extreme climate events depends strongly on local factors, but these have not been systematically studied in New Zealand. In this study, we will quantify relationships between extreme rainfall events and water-borne enteric infections and investigate the impact of local factors including land use, source water and type of water supply. We will define policy-relevant parameters for water regulators, including local climate thresholds for use in early warning systems and national maps of community vulnerability, both currently and under scenarios of future climate change and freshwater policy.