does power steering return line have to be submerged?

im doing a swap on my 01 RS, and instead of having a WRX/STi power steering reservoir flopping about my engine compartment, i want to make a custom reservoir. i noticed on the WRX reservoir that the return inlet is at the bottom of the tank

so question is, does the return line from the rack HAVE to be submerged for the system to function properly?