Business and homeowners using natural gas expect their gas companies to be doing everything they can to ensure their safety. But Team 5 Investigates found two of the three major gas companies in Massachusetts falling short on following regulations designed to protect homeowners. For decades, gas companies have been required to inspect the piping that comes into homes and connects to gas meters. They're supposed to check every three years for corrosion and every five years for leaks. "There are hundreds of thousands of homes that have not been inspected," said Mark McDonald, president of the New England Gas Workers Association.