In the coming decades, ambient temperature increase from climate change threatens to reduce not only the availability of water but also the operational reliability of engineered water systems. Relatively little is known about how temperature stress can increasingly cause hardware components to fail, quality to be affected, and service outages to occur. Changes to the estimated-time-to-failure of major water system hardware and the probability of quality noncompliance were estimated for a modern potable water system that experiences hot summer temperatures, similar to Phoenix, AZ, and Las Vegas, NV. A fault tree model was developed to estimate the probability that consequential service outages in quantity and quality will occur. Component failures are projected to have a percent increase of 10-101% in scenarios where peak summer temperature has increased from 36 to 44 °C, which create the conditions for service outages to have a percent increase of 7-91%. Increased service outages due to multiple pumping unit failures and water quality noncompliances are the most notable concerns for water utilities. The most effective strategies to prevent temperature-related failures should focus on monitoring and correcting chlorine residual and disinfection byproduct concentration, and on cooling pumping unit motors and electronics.