Backflow testing is a plumbing service that checks the backflow preventer device by assessing its pressure levels. Backflow is when contaminated water has reversed flow and entered clean water lines, which can occur at any cross-connection between clean and dirty water lines and is typically caused by a significant change in water pressure, such as from a burst water main. Backflow prevention and testing is a necessity for apartment and condominium buildings, restaurants, and other public places, and local municipal codes often require annual testing. A safety device can be installed to prevent backflow from occurring, and in the case of an unexpected or dramatic change in water pressure, this device will stop dirty water from entering the clean water supply. However, this device must be properly installed and tested to ensure that the clean water line remains free of contaminants. Backflow tests examine the backflow preventers to ensure theyre working properly, and each backflow preventer should have specific dates marked on them, indicating when they need to be properly tested. The primary reason why backflow tests are essential is because of health concerns. If water travels backward, contaminants from the sewer system can pollute it, making it unsafe. Backflow testing needs to be done by a certified company, and it is mandated by the state of Virginia that annual testing be conducted by a certified backflow testing company.