The energy comes from the work done when the surface of water was broken, plus the already existing kinetic energy of the water, and the localized energy in the

The energy comes from the work done when the surface of water was broken, plus the already existing kinetic energy of the water, and the localized energy in the wall of tube. (Basically getting the surface of the tube wet is energetically more favorable than not, so this means there's a hidden/latent energy there.) As others mentioned it's ultimately mediated through EM forces between molecules. ( https://en.wikipedia.org/wiki/Capillary_action https://en.wikipedia.org/wiki/Capillary_action )