D&D 5E How do you make sewer dungeons believable?

[Fauchard1520]

This is a silly setting problem to have, but it's recently come up in my megadungeon game. Or more specifically, in the small town beside the megadugenon. How do you make sewer dungeons believable?

To the best of my knowledge, medieval sewers were little more than open air ditches. Rome's Cloaca Maxima is a good model, but it's the sewage system of a world capital. I doubt that my little dungeon-adjacent village could justify such an engineering project. So when you're in a village setting rather than a major city, how do you justify sewer dungeons? Or are you better off inventing some other kind of subterranean labyrinth and saving yourself the verisimilitude hassle?

(Comic for illustrative purposes.)

 

[iserith]

I think the trick is to never let realism get in the way of a fun session of D&D. It's a game of make-believe after all. So make yourself believe it!

 

[Undrave]

This is a silly setting problem to have, but it's recently come up in my megadungeon game. Or more specifically, in the small town beside the megadugenon. How do you make sewer dungeons believable?

To the best of my knowledge, medieval sewers were little more than open air ditches. Rome's Cloaca Maxima is a good model, but it's the sewage system of a world capital. I doubt that my little dungeon-adjacent village could justify such an engineering project. So when you're in a village setting rather than a major city, how do you justify sewer dungeons? Or are you better off inventing some other kind of subterranean labyrinth and saving yourself the verisimilitude hassle?

(Comic for illustrative purposes.)

Maybe the sewers were there first? They are the ruins of a bigger city that used to sit where the tiny village is (probably connected to the Mega Dungeon), and the people just connect to them haphazardly because there's always a stream of water going through and they don't even know where all the tunnels go?

 

[Eltab]

The area that is today a village used to be the rich section of town, hence the sewers. Centuries of warfare plague forestfire decay migrations what-have-you leaves a nice plot of unclaimed land where new houses can be built. Somebody finds a sewer tap and figures out what it is for. The village VIPs build their houses over other sewer taps.
There are a few more taps to be located. And they just located an exit big enough for people (and monsters) to get in.

 

[DemoMonkey]

How do you make sewer dungeons believable?​

A very unpleasant potpourri centerpiece.

 

[LordEntrails]

Or a moderately capable wizard used to live in the village and spent a few months of magic to make a sewer system that would server the future growth of his home town and keep the village clean?

But actually, I wouldn't do a sewer dungeon in a small town. Maybe more like a system of caves or such, but not a proper engineered sewer.

 

[Oofta]

Some cities have a significant amount of catacombs or actual mining beneath the city. Some cities such as Naples Italy are built on top of a type of stone that is quite useful for building so they've created large caverns underneath the city.

I justified "dungeons*" underneath one of my cities in such a way, some of the caverns have been long forgotten, in other cases sewers will "break through" to some of those forgotten caverns.

*Not that I do straight dungeon crawls very often, more lairs for bandits or monsters to hide in.

 

[aco175]

If it is a small town, I may have the town well hide catacombs that contain something. It is an old trick, but players like it. I tend to throw in a catacomb with a few undead and maybe a secret passage to someplace. Most townsfolk would know about something unless a recent event like a earthquake or floods opened up something and the water stopped.

 

[Tonguez]

If you want believable then Outside of major cities you don’t have them.
that said the oldest parts of the Sewers of Paris dates to 1370. Most sewerage was just a channel in the street pouring into a natural creek or stream. Remember too that solid waste was kept in cesspits and then dug up for use as fertiliser and later saltpetre (especially when gunpowder was discovered)

The channels/streams were eventually covered over to keep the smell contained.

so generally small cramped unhygienic, prone to flooding and discharging to a natural bog outside of the town

 

[QuentinGeorge]

I have a home base that is set in a fairly new settlement with extensive sewers. The "sewers" are, of course, the remnants of an earlier civilisation, which the current inhabitants have just started repurpose to dump their sewage in. It works, and it has precedent (The roman sewers and other pieces of infrastructure were extensively used in the middle ages. There wasn't really new sewers built until the 19th century).