I guy I know does water main service line installs. Last year he had a commercial job installing a 4" fire sprinkler line and rpz. When the county came to test it failed the flow test. He sent a camera down the line line all the way to the county valve to look for obstructions. Then the county shut down the street line so the valve could be opened. They found that when the boys from the county did the wet tap they didn't cut all the way through and a piece was left in place and restricted the flow.
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