Which of the following should be documented during backflow testing?

Documenting test results, date of testing, and device serial numbers during backflow testing is crucial because this information serves as a formal record of the testing process. The test results provide immediate data on whether the backflow prevention device is functioning correctly; if it fails the test, appropriate corrective actions can be taken. The date of testing allows for tracking compliance with inspection schedules and maintenance requirements, ensuring that the device is checked at recommended intervals. Additionally, including device serial numbers ensures that the documentation is specific to the particular unit being tested, facilitating easy reference for future tests and maintenance activities.

While each of the other options might hold some relevance in various contexts, they do not cover the essential and specific documentation typically required in backflow testing protocols. The name of the installer is not as critical to the testing process itself as the results and related data. The type of water source may be relevant information but is not a direct requirement for the testing record. Previous maintenance records could be useful, but they are more related to the history of the device rather than the immediate testing process, making them secondary to the primary results of the current test.