What is the downside to having longer runs

[TheMagicalWallaby]

I am getting into custom liquid cooling, and I was wondering what is the issue with longer runs. Why are they not recommended. I am guessing that it is because you want to water reaching its destinations as soon as possible. Correct me if I am wrong.

 

[damric]

head loss

 

[damric]

http://www.engineersedge.com/fluid_flow/head_loss.htm

In case anyone is wondering what is head loss.