How to determine jfet source bypass capacitor voltage rating?

[substitute]

I've breadboarded the ol tapeop jfet hampton circuit, it's working fine and sounds excellent. The 470uf bypass cap's voltage rating isn't specified in the schematic . Is there a rule of thumb for determining this value? The parts I'm using on my breadboard version are over speced and physically much larger than I'd hope to use in the final build.

https://tapeop.com/interviews/37/diy-jfet-mic-pre/

Thanks