If you live in the country, or even in some city areas, you may use a septic system instead of a municipal sanitation system. According to a recent article published on Resilience.org, rising sea levels near the coast have the potential to make millions of these systems near the coast nonfunctional, leading to the escape of wastewater and harmful bacteria into coastal waters. At the same time, municipal water plants are usually built along water bodies like streams which not only may be impacted by rising sea levels if they are near the coast but also may feel the impact of heavier rains and flashier stream flows if future trends towards more intense rainfall occur.
You can read more about how septic systems work and how higher sea level and rising water tables would affect them at https://www.resilience.org/stories/2016-09-28/climate-change-will-cripple-coastal-septic-systems.
