According to IRC, for supply system testing. You have to test using the maximum working pressure (80 psi) of water, or 50 psi of air. And you have to maintain the pressure for 15 minutes.
For air testing drain-waste-vent (DWV) systems, you have to maintain 5 psi for 15 minutes.
Contact your local government, to find out what they require.
International Residential Code 2012
Chapter 25 Plumbing Administration
Section P2503 Inspection and Tests
P2503.5.1 Rough plumbing.
DWV systems shall be tested on completion of the rough piping installation by water or for piping systems other than plastic, by air with no evidence of leakage. Either test shall be applied to the drainage system in its entirety or in sections after rough piping has been installed, as follows:
- Air test. The portion under test shall be maintained at a gauge pressure of 5 pounds per square inch (psi) (34 kPa) or 10 inches of mercury column (34 kPa). This pressure shall be held without introduction of additional air for a period of 15 minutes.
P2503.7 Water-supply system testing.
Upon completion of the water-supply system or a section of it, the system or portion completed shall be tested and proved tight under a water pressure of not less than the working pressure of the system or, for piping systems other than plastic, by an air test of not less than 50 psi (345 kPa). This pressure shall be held for not less than 15 minutes. The water used for tests shall be obtained from a potable water source.
Chapter 29 Water-supply and Distribution
Section P2903 Water Supply System
P2903.3.1 Maximum pressure.
The static water pressure shall be not greater than 80 psi (551 kPa). When main pressure exceeds 80 psi (551 kPa), an approved pressure-reducing valve conforming to ASSE 1003 or CSA B356 shall be installed on the domestic water branch main or riser at the connection to the water-service pipe.