Waterdeep/Sewers

The sewers of Waterdeep were a sanitation system of tunnels beneath the city that connected to most locations throughout the city, including its dungeons.

Structure
The depth of these sewers varied around Waterdeep, due to Mount Waterdeep and the plateau the northern portion of the city was built upon. The Field Ward, the harbor islands, and the heart of Mount Waterdeep were the only areas in the city that the sewers did not run beneath.

Partially due to city’s ever changing layout, the tunnels of this sewer system did not match up with the routes of the city's streets by the 14 century DR.

Functionality
Refuse, as well as air, were brought down into the sewers by numerous feeder pipes scattered throughout. These pipes measured less than in diameter.

The sewer network operated on a system of tidal flushing, meaning that its waters were flushed out by the ocean tides that came into Deepwater Harbor. The sewer's tunnels emptied into the harbor at places that were covered by extremely large and strong gratings. These places were purposely difficult to access, as the sewer network's designers sought to hamper the movements of less desirable visitors from the sea and to prevent the sewers from being used by criminals as an underground highway.

The areas in which the sewer network was constructed at, as well as the varied sizes within, were designed to optimally account for the ocean tides. Their layout was also dictated by where springs rose and flowed down to the sea. And finally, to ensure the city's harbor did not become a cesspool, Ahghairon and other mages bound spells into the city's wards that assisted the flows of water in carrying away sewage.

Interior
The ceilings, floors, and walls all throughout the sewer system were made of masonry. There was little to no lighting within the sewers and a terrible stench pervaded the entire network. Gratings in the sewers were all quite thick stout. Some were permanently set into the stone walls, while others could swing open on pivots. By the 14 century DR many were suffering from rust.

The passages of this sewer network were denoted as beither one of two types based on their size, primary and secondary. The first were easily navigable, while the other type required human-sized creatures to crawl or swim their way through. Those who worked in the sewers were known to navigate passages by laying down boards as temporary bridges or by vaulting across ledges with catchpoles. The latter of which were carried in order to reach below the water and clear debris from gratings.

Primary passages measured across and had parallel,  wide, walkway ledges that lacked rails. Secondary passages measured and had on one of its sides, usually the more easterly or southerly side, a single  wide ledge. Besides these two types of passages there were many older, smaller passages that had over time been put out of service and walled up by the 14 century DR.

Junctions Rooms & Surface Shafts
Some areas connected between primary passages, known as junction rooms, were square in shape. They measured by, were  tall, and had a sitting ledge near their ceiling.

Entrances into the sewer network were known as surface shafts. They measured in diameter, were typically spherical in shape, and had iron rungs set in the walls for use as ladders. They were capped by covers made either wholly of metal or of metal-banded wood.

The surface shafts and junction rooms of this sewer network (as labeled on the map above) could be found at the following locations:
 * Safehaven: An inn in the Southern Ward, in its cellar was a hidden ladder leading down to the sewers. This was hidden behind a tall door that opened upon turning upward the spigot on the last wine casket.
 * SF1: A surface shaft underneath trees in the interior of the block northwest of the shrine to Silvanus within the Shrines of Nature.
 * SF2: A surface shaft in the northernmost corner of Sabbar's Alley.
 * SF3: A surface shaft in the center of Shank Alley.
 * SF4: A surface shaft south off the Street of Glances and just south of the tree in Sniff Alley.
 * SF5: A surface shaft in the central stand of trees in the southern end of Heroes' Garden. Halfway down this shaft was a secret entrance leading to the Catacombs of Yintros.
 * SF6: A surface shaft under a lone tree in the alleyway west of Eltorchul Villa, south of Ivory Street and north of Pharra's Alley.
 * SF7: A surface shaft in the mouth of an alleyway opening north off Chasso’s Trot, just west of Sul Street.
 * SF8: A surface shaft in a cul-de-sac due south of Jhansczil Villa.
 * SF9: A surface shaft underneath a tree, in an alleyway just south of Brossfeather Villa.
 * SF10: A surface shaft just south of the Ilitul Villa, at the northern end of a dead alley opening off Grimwald’s Way.
 * SF11: A surface shaft just west off Mendever Street, in the easternmost cul-de-sac that opens off the alleyway bounding Nesher Villa.
 * SF12: A surface shaft in an alleyway just west of the gates of Manthar Villa, off Delzorin Street, between Sul Street and Shield Street. Opens into a junction room.
 * SF13: A surface shaft in the alleyway within the block surrounded by Copper Street, Delzorin Street, the High road, and Vordil Street.
 * SF14: A surface shaft in Trollskull Alley, southwestern corner, near the intersection of Delzorin Stret and Whaelgund Way.
 * SF15: A surface shaft in a cul-de-sac north of Horn Street, between Tower March and Whaelgund Way.
 * SF16: A surface shaft at the intersection of Sharra's Flight and the Street of Whispers.
 * SF18: A surface shaft in a cul-de-sac opening northeast off of Toalar's Lane.
 * SF19: A surface shaft at the intersection of Calamastyr Lane and Gothal Street. Opens into a junction room.
 * SF20: A surface shaft at the southwestern corner of Runer's Alley.
 * SF21: A junction room without any surface entrance, located under the southern mouth of Cloaksweep Alley.
 * SF22: A surface shaft in a copse of trees at the center of a block bounded by Copper Street, Hassantyr's Street, the High Road, and Julthoon Street.
 * SF23: A surface shaft at the western end of Marlar's Lane.
 * SF24: A surface shaft at the base of a rocky cliff-face, just behind Blackstaff Tower.
 * SF25: A surface shaft near the top of the rocky slope of Mount Waterdeep, at a point due southwest of Turnback Court.
 * SF26: A surface shaft located in Turnback Court. Opened into a junction room.
 * SF27: A surface shaft located in the southwest corner of an alleyway that opened south off Cymbril's Walk, at the intersection of Street of Silver and Warriors' Way.
 * SF28: A surface shaft located in the southwest corner of a dead-end alley, in the block bounded by Lamp Street, the Street of Bells, Cymbril's Walk, and the Street of the Sword. Opened into a junction room.

Groups of Interest

 * Cellarers' & Plumbers' Guild: Most members of this learn the general layout of the sewers after two to five years. This is because their primary concerns were keeping the sewers of the city functional and safe, with guild members being engaged in constant small repair jobs in the sewers, such as on plumbing in old buildings.
 * Dungsweepers' Guild: This guild normally did not work on the sewer system, but for security reasons the city reserved the right to contact the guildmaster and hire members to help in such work.
 * Guild of Watermen: Members of this guild knew various spots where the sewer system emptied into the harbor.
 * Merfolk: Living within Deepwater Harbor, these people regularly patrolled the areas where the sewers emptied. They would use pole mounted catch-nets to scoop up and gather any debris they found into large tow-globes, which they then used to transport the debris far out to sea.
 * Unseen: This secret society operated out of both the sewers and Rat Hills for decades, but following the Rat Hills Conflagration they began having their main meetings within secret rooms in the sewers. Their leader, Hlaavin, also kept many safe houses within the sewers.
 * Xanathar's Thieves' Guild: This guild had safehouses scattered throughout the sewers, hidden by secret doors. Tunnels were often marked with the symbol of the guild in yellow chalk, helping to guide members to the safehouses. Every few days these were erased, either by members of the guild or by the Dungsweepers' Guild.

History
During the days of Ahghairon, a number of Underdark creatures tried to invade the sewers and Waterdeep proper by means of a portal within Undermountain, which he put an end to by means of the gatewarp spell.

In 1358 DR, during the Time of Troubles, the mortal avatar of Myrkul opened a portal between Hades and the Prime Material plane. Hoards of undead came rushing out through the sewers and up into the Dock Ward. The guardsman Ylarell tracked these undead and in the process was slain by Myrkul.

In Eleint, 1367 DR, new creatures began to be encountered in the sewers by members of the Plumbers' Guild, such as the sewerm. Some of these new creatures originated from the Rat Hills, having fled into the sewers following the Rat Hills Conflagration.

In 1369 DR, during the event known as Halaster's Higharvestide, a number of creatures crawled out from the sewers and terrorized the people of Waterdeep.

That same year the city faced an attack by the forces of Iakhovas and in its wake a number of sea creatures escaped into the sewer system. A trio of aboleths, hailing from the Swordsea Depths, joined in this assault for the sole purpose of gaining access to this sewer system.

In 1492 DR, Jeryth Phaulkon sent awakened rats into the sewers to search for Xanathar's hidden lair, eventually discovering a secret spiral stairwell in the sewers beneath the Castle Ward.

Rumors & Legends

 * Some rumors claimed that the cellars of some of the City Watch's guardposts contained secret entrances to the sewers.
 * There were persistent rumors that Uluryk Malogh made an extensive map of the city's cellars and sewers, detailing all their various barriers, locks, and traps.
 * Around the mid-14 century DR, there were rumors circulating that Xanathar's Thieves' Guild had trained guard rats roaming the sewers and that slavers dwelling within the uppermost rooms of Undermountain creeped out into the sewers at night to kidnap unsuspecting Waterdhavians.

Appearances

 * Adventures
 * Waterdeep • Undermountain: The Lost Level • Waterdeep: Dragon Heist
 * Undermountain: Stardock • Expedition to Undermountain
 * Novels
 * Waterdeep • Escape from Undermountain • The Abduction • The Diamond • Rising Tide • Silverfall, "Lady Cassalanter’s Busy Day" • Daughter of the Drow • City of the Dead • The God Catcher • Circle of Skulls • Timeless
 * Windwalker • The Shadowmask • Elminster Enraged
 * Video Games
 * Eye of the Beholder • Dungeons & Dragons: Eye of the Beholder
 * Video Games
 * Eye of the Beholder • Dungeons & Dragons: Eye of the Beholder