A new plumbing system is being pressure tested. The test must be conducted with water (or air, except for plastic) at a minimum of 100 psi for at least 15 minutes. What is the exception regarding the test medium?

• Except that the test pressure can be reduced to 80 psi for residential systems.
• Except that water testing is not permitted for copper piping.
• Except that air testing is not permitted for plastic piping.
• Except that the duration can be reduced to 10 minutes for small systems.