All certified backflow prevention assembly testers play an important role in protecting the City of Houston water customers. The tester's role is to verify the proper operation of the assemblies. For this reason, all certified backflow prevention assembly testers are responsible for the accuracy of their field-testing and of their Test and Maintenance Reports. In addition to this the tester is held accountable to not alter the design, material or operational characteristics of a backflow prevention assembly during repair or maintenance without prior consent of the City of Houston. The following links provide valuable information that every tester should know.