My private well is not gravity-fed, the storage tank is at ground level. It runs the pump to keep the tank filled which also maintains pressure. Two consecutive flushes of a low-water toilet* is sufficient usage to trigger the pump and involve electricity.
The aerobic septic system also involves electricity to run the aerator and the discharge pump, and the timers that operate them.
I've spent a little over $10,000 in maintenance and repairs in 20 years, huge majority of which is on the septic, plus the electricity to run them.
*The toilets are rated at 1.6 gal for a flush but there have been flapper and/or fill valve repairs on all of them so I can't say if they're still accurate on that point.