When is a main drain test required?
A main drain test is required annually or any time the water supply control valve is closed, this includes any time a system undergoes maintenance or repair. This test is essential to ensure that the water supply valve is fully open. Sprinkler systems perform exceptionally well, however when they do fail the major cause of failure (35% of the cases reported to NFPA) the water supply valve was closed, thus the verification of an open water supply valve cannot be over emphasized. The annual test frequency is a minimum requirement, NFPA 25 permits more frequent testing if desired.
