Sam is not at a scale where this would be a problem. He might be much smaller than a regular human, but like a mouse, he’s a small mammal that would drink the water. Mice are smaller than Sam and are able to drink water without an issue, as we can see by their survival for millennia. 

The surface tension of the water (what makes it ‘sticky’), is not too strong for them to drink. The same goes for Sam’s people. The smallest living mammal is barely 2.5 inches long at its longest, and these shrews do not choke on water when they drink. If we go smaller than an inch for scale, perhaps the cohesion of water might begin to be an issue for survival, but my fics never go down to this scale.

Another factor in any gt story is ‘suspension of disbelief,’ a term embraced by all science fiction writers. Certain parts of gt are not supportable in the real world, no matter how much we wish it so.