Hello. I've made a sewer map for VTTRPG's. It was made with photoshop and many of the -awesome- [2 minute Tabletop](https://2minutetabletop.com/) assets pack.  
The specs I thought for it were:

* In a \~6m|20ft radius around the light shafts (the manholes from the street perspective), dim light (perception penalization), darkness for the rest (that's why the map is so dark, to convey that idea).
* The height of the corridors is about 3m|10ft. To reach the manholes is a difficult task  (because I want them in the sewers!), but it's up to you: may be this map could be a recurring way for the party to shortcut through the city above (?).
* The gangway in the corridors is \~1m|3ft. The players must go in line.
* The water between gangways is \~2m|7ft, so only the "strong" can jump without a previous run.
* The depth of the water in the corridors is 3m|10ft . Can be dangerous but (I hope) not deadly. The strength of the running "water" is up to you (although it can't be that strong I think, unless there were a heavy rain or something... you'd be more creative than me!). The depth in the pools can be a lot more dangerous I suppose.
* The Letters. To avoid been linear I add this "impossible" connections between the corridors (may be a Int check to not get lost?).
* The wall-shortcuts. This are for the players to discover (it can be because the char made a good perception roll, but also because the player notes it). In my game, I put some other maps in between, trying to make it more confuse and exciting (actually I liked those maps and wanted to use them anyway!).
* The pipes can hold a (medium) character fine, but count as "difficult terrain". May be they could be slippery enough to be a peril.
* In the room besides the pools, I put a temple but it can be a hideout or anything (I'm thinking about make a few more options for you to choose but we'll see if my life agrees with that). The pool/fountain in the middle can be use to trigger the "trap" (i.e. when the blood reaches the graves, the statues come to life when the party loot/desecrate it (?) ...I know, I'm not too fancy or innovative but it was fun in my session), in my case I chose not to use the trigger mechanic to save some session time.
* The broom-room. I've hided the -true- loot in here. I thought of it as the "safe long rest" place, and in a way to reward the party for exploring and look out for a safe (and "realistic") place to rest and regroup.

The encounters are up to you, I've used some wererats, some [cakers (we're in sigil, so this is my/the under-sigil actually)](https://5e.tools/adventure.html#tofw,1,undersigil,0) with their reflections and some tooth fairies ('cause, why not). There's a lot of *baddies* that the party can cross paths with in the sewer, even toxic fumes and so, or some horrors beneath the green putrid water...

Enjoy

Sewer Battlemap