First who writes these descriptions?

A sewer is gravity fed. Open to the atmosphere. Little to no pressure unless there's a a whole bunch of hills and even then there are catchments to slow the water to a reasonable speed.

Potable water on the other hand is pressurized. When I ran tests on water pressure for hydrants we measured from 85PSI to 110PSI on 8 inch mains. Plenty of energy to create havoc.

Mark