Vinyl fencepost for sewer hose storage

Use a Deburring tool.

Drill the holes in the top and let liquid evaporate
Heat a piece of pipe with a portable propane torch and melt holes in the bottom if you must
Good Luck, Mike
PS hold the pipe with vice grips

Why not sand them down a bit? You could rig something up where you used a broom handle or something to extend the reach of your sand paper.

Ya know, that's a darn good question. I sure never thought about it when I did mine. I guess in hindsight I would only drill the holes closer to the openings where I could reach them to deburr them and let the natural back and forth around corners and such to drain.