I've experienced this recently and if it's a bug then here you go:
This doesn't happen with the default resource pack. When this error happens, I am using a 128px resource pack.
When I move away from water (say about 10-20 blocks) it simply disappears. The shadow is still there so I can see where the water would be, but the water is not actually rendered.
If I move back towards the water, it will reappear.
When this glitch occurs, it affects all visible water, there seems to be a limit on how close you have to be to water before it renders, and if you are outside this range, it all disappears at once.
Duplicate of MC-32287 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.