I googled:
Meaning and explanation: When you are determined not to do something because it would be either undesirable, painful, or bad, then you can say “Come hell or high water, that is not going to happen”.
This can be used in arguments, especially where passion or anger are present.
Examples:
•Come hell or high water we can’t close down the office in New York. We shall close all other branches before that one.
•There was no way President Bush was going to do nothing after 9-11. Come hell or high water he was going to make someone pay for it.
'hell and high water' to me symbolize DEATH no matter how you look at it.
I could also compare (to my opinion) 'hell & high water' to this following example:
"I will succeed even it'll cost my life"
therefore, "hell & high water" does not merely means obstacle or difficulties, but pain (and even death)....
:)