This paper is devoted to present reliability techniques as a best failure mitigation tool for CNG composite pressure vessels. As far as composite materials are so sensitive to environmental working conditions, design methodology must be established based on reliability considerations. Because of over using of car fuel tanks, CNG should be properly substituted as an alternative fuel. Safety and cost are the most critical points in developing CNG-CPV to public usage. Meeting optimum point, design criteria must be followed by reliability criteria. In this paper, author tried to persuade CNG-CPV developer to take care of mentioned risks. Reliability testing is introduced as a feasible and reliable solution in order to assure desired safety.