What type of pipe can used on a water heater pan drain?

You can use 3/4" or 1" PVC pipe for w/h pan run off line. Terminate on the exterior of the house.

I would personally use SCH40 (schedule 40) PVC. I don't use the black plastic pipe for anything and I only use CPVC for pressurized water. Some may say its over kill to use SCH40 for a drain pan drain, but it's really all I use for any drain, downspout or sump application.