The United States Cybersecurity Infrastructure & Security Agency (CISA) has issued a formal warning on ransomware threat actors targeting water and wastewater facilities (WWS), citing several incidents so far this year. A joint bulletin released by the CISA, Federal Bureau of Investigation (FBI), Environmental Protection Agency (EPA), and National Security Agency (NSA) stated, “This activity—which includes attempts to compromise system integrity via unauthorized access—threatens the ability of WWS facilities to provide clean, potable water to, and effectively manage the wastewater of, their communities”. In the last year, there have been several major attacks against water facilities. One attack occurred in March 2021, when an unknown threat actor deployed a ransomware variant at a Nevada-based WWS plant. In July 2021, a ZuCaNo ransomware variant was deployed on a SCADA computer at a Maine WWS facility. In August 2021, a Ghost ransomware attack occurred on a California WWS facility. One of the major breaches that pushed this warning was an attack in February, where an intruder broke into a computer system and remotely altered system settings to increase the chemical release of sodium hydroxide into the water supply. CISA encourages IT and security teams to only permit access to individuals who absolutely need access, as well as implementing multi-factor authentication, as well as segmented networks to prevent lateral network movement, and failure control systems.