pressurize

So, now habitats need to be pressurized and filled with an artificial atmosphere made of nitrogen and oxygen -- Which comes with more problems.

So, the oil inside the pipe is pressurized (usually around 14 times normal atmospheric pressure or over 200 PSI) to ensure that no bubbles can form.

Elevated storage is also beneficial during a power outage, by keeping the system pressurized even when pumps are out of service.

At each end of the transmission line is a plant filled with pumps and tanks to pressurize and often to circulate the dielectric oil in the pipe.

Those elevated tanks, whether they are water towers or just ground-level basins built on hillsides, act kind of like batteries to make sure the water distribution system stays pressurized even if pumps lose power.