It's just not generally done over long distances. Oil is pumped over long distances, but it's also much more valuable. For water, we rely more on cheaper ways of transporting it, and transporting it over shorter distances, using things like aqueducts and, yes, pipelines.
Here's an example of a big water pipeline project:
https://en.wikipedia.org/wiki/Northern_Cyprus_Water_Supply_P...
There are many issues with transporting large quantities of water vast distances. From legal (it is illegal to transport water from the Great Lakes to outside of their basin), to physics (water is expensive to pump up and over mountain ranges and building tunnels is incredibly expensive.
Basically, just like there are only so many places that it is cost effective to build dams or pumped hydro electricity storage, there are only so many places that it is cost effective to build pipelines.