Enema as an emergency water hydration process

My professor in college once mentioned in passing a story about a person who got stranded in an island after a shipwreck. There wasn't a lot of drinkable water, and the ones that he found were mostly in muddy pools or even in dirty puddles. He didn't want to risk drinking them, because they may upset his stomach and become sick, leaving more problems for him. So instead, he salvaged some parts from the shipwreck and used an enema to put the dirty water directly into his lower intestines, bypassing the stomach and hydrating his body in the process. Do you think this is feasible if the person wasn't a health care professional or anyone with a background in medicine? How plausible do you think is this story?