You don't need to use your water pump when connected to city water. That should have been covered in your PDI unless you bought from a previous owner and they neglected to mention it. Many times using the two together can cause problems by jamming the check valve at the pump thus filling the fresh water tank.
It has nothing to do with brownout conditions. Check your pedestal breaker by turning it off then back on. If that doesn't fix it then check the main breaker inside your RV by following the same procedure.
I have never used my water pump except for winterizing.
Richard & Jill
2014 Flagstaff 832IKBS Classic Super Lite
2018 Silverado 1500 Crew Cab Z71 4WD All Star Edition
Camping since 1989, seasonal since 2000
Car Shredder Op/Tech, Scrap Metal Recycling - retired
The Faster I Go, The Behinder I Get.