South Wales firefighters need to be retrained on how to tackle fires.
Chief Fire and Rescue Advisor and Inspector for Wales, Dan Stephens told BBC firefighters will have to "unlearn" two decades of tactics. Outdated tactics partially introduced 30 years ago were not scientifically proven even then.
"We have serious concerns that the adverse safety events that can result from this are not being recognised, let alone being reported," Stephens said.
South Wales Fire and Rescue said, while the report was concerning, it was grateful that criticism was directed at tactics and procedures and not frontline firefighters.
The Welsh government said all three of Wales' fire authorities needed to act on the findings and implement them by July 2025.
Investigators determined the service's current tactics at a "substantial number" of incidents had placed firefighters at unnecessary risk and resulted in avoidable property damage after looking at 252 incidents between 1 April 2021 and 31 March 2023.
Cabinet Secretary for Housing and Local Government Jayne Bryant, said: "There is no criticism in the report of frontline firefighters, who continue to do their utmost to protect life and property.
"The issue is about how firefighters are trained, equipped and the tactics employed to fight fires."
Many of the methods used by the fire service were "disjointed, contradictory and, in some instances, scientifically incorrect," authors wrote.
