Tustin is the latest city to hike water rates for residents this year, but they have a different reason than many of their surrounding cities – some of the drinking water might not be safe.  Due to concerns about chemicals called polyfluoroalkyl substances in the city’s groundwater, also known as “forever chemicals,” city leaders shut off five of the city’s wells, forcing them to import nearly half the city’s water from out of town.  While none of the city’s wells exceeded state regulations on forever chemicals, they were coming up near the limit, as the city also wrestles with leftovers from the Marine Corps Air Station Tustin base that might’ve poisoned much of the city’s groundwater over several decades of chemical dumping.