Sewer

Sewers, also known as sewer systems, were underground pipe or tunnel systems built beneath cities for the purpose of transporting away wastewater or "sewage" to somewhere else for disposal or treatment. These were essential to most large civilized settlements, as not disposing of wastewater could create a breeding ground for diseases.

"Belike you keep a pot by your bedside and cast out the leavings into a communal pit of a morn . . . Many cities have dispensed with such simple methods of hygienic living, and instead the waste of inhabitants comingles and flows through great channels beneath the very streets."

- An excerpt from Lessons for Sensible Living IV: Cities and How to Survive Them.

Construction
Sewers were often dug and constructed as cities were planned and built. In the case of rather older cities, sewers may have been excavated after their street layouts were already in place.

Some cities sported sewers that were, in part, the repurposed structures of older cities they were built atop of. Such examples of this included the former city of Sarbreen beneath Ravens Bluff and the former deep gnome city that Calimport stood atop of.

The simplest form of sewer system consisted of various drains and grates&mdash;located in streets, alleyways, and some homes&mdash;that emptied directly into an underground river or cistern. The next step up from that were sewers consisting of stone halls, large enough to allow for maintenance, featuring clay or metal pipes. These could become rather mazelike and confusing to navigate.

Functionality
Cities that stood close to rivers or tidal bodies of water often chose to design their sewers to operate on a tidal flushing system. This meant they utilized their nearby source of moving water, diverting it so as to flush local wastes away to elsewhere. This was often the cheapest & easiest route for such cities to take, but it could cause problems for those downstream from them.

In order to prevent severe clogs, many sewer systems installed screens across their channels to "catch" large debris, which would then be cleared and have their debris taken to the surface by city workers. Sometimes these screens had spikes jutting out, which served to both catch more debris and dissuade those illicitly traversing sewers from getting up close to the screens and tampering with them, such as with things like acid or files.

When such screens were installed throughout much of a sewer, they had the effect&mdash;from the point of view of those who regularly traversed sewers&mdash;of dividing it into segments. With city crews working on particular segments and criminals finding them to be frustrating barriers to what would otherwise be an ideal covert highway.

Bathrooms
In most cities in the Realms, buildings had indoor toilet rooms that connected to the sewers. In the case of grand houses and castles, these toilets were known as garderobes. In most other cases, toilets were known by the less formal name of "jakes." Outdoor toilets were known variously as gloryhouses, thunder thrones, and privies.

Those indoor rooms typically consisted of a toilet seat with a gravity drop pipe descending beneath it. Nearby would be a wiping cloth for users, to be washed for later use, as well as large jugs of water with which to wash and flush down waste. Waste would then be carried down the pipe to a wastewater cistern with a turn-the-balun connection to the sewers beneath. Otherwise known as a "float valve," this innovation developed by Burlan Almaether made it so that if liquid levels in an enclosure ever reached a certain point, the flow of water would be shut off, thus protecting cellars from sewers backing up.

Typically, outdoor privies in the Realms did not connect to the sewers, but in certain cities a direct connection was oftentimes the case.

Hazards
Sewers often had a strong stench within them, making it difficult for many creatures to smell much of anything, potentially even causing nausea. Though those who made a living in sewers eventually became accustomed to it. Beyond mere smell, sewers often incubated various illnesses, referred to broadly as "sewer plagues." One particular disease being filth fever.

In areas where there was poor ventilation, pockets of methane gas were likely to form from the waste in sewers.

Prevalence of Sewers in the Realms
All of the cities on the continent of Faerûn that were noted as having sewers were as follows:
 * Alaghôn, Alamontyr, Ankhapur, Archenbridge, Athkatla, Berdusk, Bezantur, Blackbarn, Calaunt, Calimport, Dagger Falls, Daggerford, Elturel, Elversult, Helm's Hold, Hlondeth, Innarlith, Ithmong, Luskan, Iriaebor, Memnon, Mintarn, Neverwinter, Nonthal, Oparl, Ormath, Phlan, Ravens Bluff, Riatavin, Saradush, Sarbreen, Saelmur, Saerloon, Scornubel, Selgaunt, Schamedar, Silverymoon's Northbank district, Skuld, Soorenar, Suzail, Tantras, Thentia, Tilverton, Urmlaspyr, Waterdeep, Westgate, Zhentil Keep.

In the land of Zakhara, the city of Huzuz was known to have a sewer. On the continent of Laerakond, the cities of Harglast and Tarmalune had sewers. And though not a city, the fortress of Candlekeep also had a sewer.

Some drow communities in the Underdark were known to have sewers, but these were never large or extensive and their waste always flowed directly to fungus beds, which in turn fed upon the sewage.

Most Notable Sewers

 * Sewers of Athkatla
 * Sewers of Baldur's Gate
 * Sewers of Calimport
 * Sewers of Hillsfar
 * Sewers of Hlondeth
 * Sewers of Luskan
 * Sewers of Mulmaster
 * Sewers of Neverwinter and its subsection, the Blacklake Sewers
 * Sewers of Ravens Bluff
 * Sewers of Tantras
 * Sewers of Tilverton
 * Sewers of Waterdeep
 * Sewers of Westgate
 * Underscar, the sewer system of Helm's Hold

History
Over the course of Toril's history, sewer systems were developed for various settlements by dwarves, halflings, and in rarer cases enterprising humans and elves. But over the course of centuries it was rock gnomes, more than any other race, who became specialized in designing, repairing, and perfecting the sewer systems of large mixed-population cities. Though the average human citizen was likely unaware of the gnomish oversight involved in their sewers. The existence of sewers on Toril dated as far back as the city of Memnonnar, which was established by the Great Pasha Memnon in approximately.
 * General History
 * Specific History

Centuries later, sewers were constructed in southeast Faerûn in the cities of Medinat Muskawoon and Phoenix as well as in northwest Faerûn by the elven kingdom of Earlann, within such cities as Ascalhorn and Myth Glaurach, followed by the Netherese Empire.

In the millennia since Memnonnar was founded, sewers continued to be constructed for cities within the Lands of Intrigue, often repurposing the ruined cities of the dwarven kingdom High Shanatar. In the years leading up to the Eye Tyrant Wars, beholders established cults within many of these sewers, planning to one day have their forces pour out and conquer the cities when they had grown strong enough.

During the time of the Shoon Imperium, most of the cities in the Lands of Intrigue that were under its rule possessed sewers, including its capital Shoonach. When Strohm I led an assault on the city in the, he had many of his forces enter Shoonach through its sewers.

Inhabitants
"A breeding ground for mucky creatures."

- Another excerpt from Lessons for Sensible Living IV: Cities and How to Survive Them.

Much of the wildlife in cities were relegated to sewers, wherein they were likely to become exposed to various illnesses and sometimes become transmitters of them. The creatures that were most often found to be lairing within sewers on Toril included chuuls, meazels, giant crocodiles, various varieties of oozes, cesspit oozes, yuan-ti, and the extaminaars. But most of all rats and giant rats. The sewers of Zhentil Keep even had their own unique strain of rat. The sewers of some of Faerûn's most ancient cities, such as that of Skuld, were haunted by ephemeral swarms. And in addition to animals and monsters, the moist, dark environment of sewers made them an excellent space for fungi to grow.

When it came to the humanoids that inhabited cities, the destitute and criminal elements of society were likely to hide in the sewers, hide the bodies of their victims, or make a home for themselves. Beggars often knew how to navigate sewers. And criminal elements such as outlaws, smugglers, thieves, and outcasts often hid within sewers of the cities. In some cases even building their own societies. Sewers were also popular hiding spots for cults to outlawed deities, such as Moander.

Organizations

 * Sometimes city officials hired adventurers, mage guilds, or wizards-for-hire to clear out or deal with monsters in their sewers.
 * All across Toril, city sewers were often utilized by great thieves' guilds.
 * The three largest rock gnome clans known for their expertise in sewers were the Barbellows, the Narlens, and the Thallows.
 * The Church of Gond's techsmiths were known to build small golems tasked with taking care of unsightly municipal duties, such as caring for large sewer systems.
 * In urban areas, the Church of Malar sometimes held holy hunts within sewers.
 * The Church of Moander often constructed temporary shrines to him within sewers, as well as temples out of forgotten areas of sewers.
 * Many clerics of the Church of Shaundakul sold accurate-as-possible maps of short underground routes, such as sewer systems.
 * The Church of Silvanus's clerics, in the Vilhon Reach region, often provided magical support free of charge to the cities in which they resided. This included keeping their waters clean and the sewers as free of disease as possible.
 * The Church of Talona's underground temples were often built atop of stinking, overflowing sewers.
 * The watchmen of any city were likely to patrol their sewers, but rarely for any extended period of time. Such examples included the City Watch, and later the City Guard, of Waterdeep and the City Watch of Ravens Bluff, which had a dedicated branch known as the Sewer Brigade.

Trivia

 * Mayors often owned maps of their city's sewers.
 * The divine realm of the demigod Raxivort was known as the Black Sewers.