In a fantasy world (a D&D setting, basically), how would an open underwater town populated by an assortment of mer-people deal with waste disposal? A few details: the town in question is a part of a larger above-ground settlement. They mainly trade fish for tools and other surface products. The dwellings are mostly carved/shaped into the coral reef in the shallow waters. The population is relatively low, around two thousand people, and likely spread-out - less an urban center and more a farming village.

Technology is, again, D&D-like, which is to say pseudo-medieval, as useless as that statement is. This being a fantasy world, "magic" could be the answer to everything, of course, and I suspect it will be needed to some extent. But I'm more interested in low-magic, somewhat natural solutions to the simple question: where does a merman poo?

  • $\begingroup$ Put a banishment enchantment on all the toilets. $\endgroup$
    – Samuel
    Commented Feb 8, 2015 at 4:58
  • 2
    $\begingroup$ Things I have managed to play DnD for two decades without considering. Man, I'm never going to be able to look at merfolk the same way! $\endgroup$
    – Cort Ammon
    Commented Feb 8, 2015 at 5:49
  • 4
    $\begingroup$ Dump it on land. Honestly, why would they care about land, much like how we dump all the stuff we don't want in the oceans. $\endgroup$
    – blaizor
    Commented Feb 8, 2015 at 6:56

4 Answers 4


Where do fish poo? It all falls down. And goes into fertilizer.

Maybe make sure you've got ridges on the ground, so any tides or water movements don't send it all everywhere.

Metals and other things get recycled heavily, since they're not common, nor easily accessible. Coral, bone, etc, get tossed on a rubbish heap, which some animals probably like to cannibalize for eats. Other organic refuse gets eaten by scavenger fish or crabs.

For indoor use, probably have designed funnels which focus outside water motions (tides, etc) to do suction and removal of things (garbage disposal chutes & ahem wastewater).

Remember that all of your mer-toilets have three seashells...

  • $\begingroup$ Dammit. You beat me. -_- $\endgroup$
    – blaizor
    Commented Feb 8, 2015 at 6:54
  • 1
    $\begingroup$ To the seashells? Gotta love seashells by the seashore. $\endgroup$
    – user3082
    Commented Feb 8, 2015 at 7:03

An ocean current could be used to keep fresh (as in, new, not as in saltless) water flowing through each house like a gentle, cleansing breeze, cleaning everything.

Slightly more advanced, the house design could funnel those parts of the breeze used for waste, into the "sewers" by the leeward side of the house.

Magic also works, of course.

In fish tanks the way it's done is a constant water current into the "sewers" (the gravel), and culturing cleaning fish, snails, weeds, etc. So, very biological coral-homes, like the tree-homes of the elves, could consume the waste products.


I think if you have a merfolk population as 'part' of a human city/town an even bigger issue would be how to keep the human waste out of the mertown? Humans sent their waste into the rivers and oceans for a long time. larger cities would make it almost uninhabitable for merfolk if certain precautions weren't taken on both sides. The first would be not to put the mertown in a delta, but around the bend. They would want a little current to help carry things away, but not to bring the sludge of the humans into town.

Their own waste of course would likely try to utilize currents, maybe even create artificial currents to carry away waste from the settlement.


I think you should remember that it is only pretty recently that human society managed to do something more sanitary with their waste than dumping it in the street, indeed in some unnamed parts of the world, this is still pretty much what happens today.

As others have suggested there probably wouldn't be any sanitation other than a strong current.

They would probably be a lot less squeamish about it than you imagine.


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