Why isn't the water level the same on both ends of a hose? When I fill the higher end of a hose till its overflowing. I can keep the lower end of the hose bout half a foot below it without water flowing out of it. The middle of the hose is all beneath the higher hose end. The crinks in the hose seem minor, especially since raising one end of the hose up and down shows changes in the water level of the other end. Why is the water level in one end of the hose able to be higher than the other end?
The hose has a diameter of bout 1 inch. Doing some napkin calculations shows that surface tension is bout 2 orders of magnitude lower than the pressure difference arising from the height difference in water levels. Which seems to rule that out. The hose is a normal garden hose.
 A: In addition to the explanation of @niels nielsen, the presence of vertical loops or humps in the hose can present a problem.
If any of these vertical loops have the top of the loop filled with air, then the levels at the two ends need not be the same.  You describe filling the hose by pouring water in one end of the hose.  This method almost guarantees bubbles in the hose.
The whole basis of a water level is that the hydrostatic pressure changes with depth in the liquid.  Introducing places where you go up through water, and then down through air trapped in the loop, throws the whole process off.
A better way to fill the water level hose is to put one end in a bucket of water, then draw some water by suction to the lower end.  Allow the syphon to run for a while, and move the hose around to eliminate humps, and get any bubbles moving.
When I use such a device to measure the slope in my driveway, I use clear plastic tubing, just so I can see any bubbles. (And I can see the level dropping and gradually slowing down to its final position.)
If you have a length of tubing, filled with bubble-free water at rest, the water levels at both ends will be the same.
A: for a long hose, the inertia of all the water in it slows down the hose's response to changes in the level of its open ends. It takes ~seconds for the water to start moving, and once it starts moving, it will persist for ~seconds more even if you immediately readjust the end heights of the hose in such a manner as to stop it.
So the question is, for how long can the ends of the hose be offset before flow is established? 1, 2, 5, 10, 20, or 50 seconds?
