Where people go to the bathroom matters a lot, worldbuilding-wise. They may use an outhouse, a chamber pot, a porcelain commode, or an advanced vacuum-flush system aboard a space station, but the infrastructure of sewage disposal informs a lot of urban planning, clothing, agriculture, public health - even diet. It’s not usually a topic most worldbuilders want to think about for fear of reverting to juvenalia, but assuming it just gets taken care of offscreen can be detrimental to setting.
Let’s take the Indus Valley Civilization for example. At 2500 BCE the city of Mohenjo-Daro had a functioning sewage system, consisting of a waste disposal/toilet hole built into a washing platform, joined by clay piping to the city’s sewage system. Flushing the hole was done by emptying a jug filled from a courtyard’s central well. The sewers emptied into cesspits, which were later raked and emptied.
This tells us much about their civilization. Firstly, that they were sophisticated and skilled enough with ceramics, brickwork and hydraulic engineering to run sewage lines from private residences into a larger, public drain while also avoiding flooding and aquifer contamination. They prized cleanliness and public infrastructure, planned where they built and had sanitation workers. That’s a lot of information from a toilet.
Toilets also inform us about clothing. Observe the voluminous skirts and petticoats European women wore from the 1600s to the 1900s. Having to use the commode while dressed such necessitated the wearing of open drawers left open at the crotch for convenience.
Consider also what they do with the resulting sewage. The ancient Romans collected urine, which they allowed to age to create ammonia. Called lant, its use continued into pre-industrial times. Lant was used to scour wool, brush teeth, flavor ale and treat wheat seed to prevent birds eating it once sown. Fecal matter can be composted to make fertilizer, or used raw as nightsoil. The use of nightsoil is hazardous. Fecal-borne bacteria can contaminate the plants grown with its use, which then sicken the people who consume them without adequate cleaning or cooking.
This brings us to sanitation and its effects on food and public health. Note the 1854 Broad Street cholera outbreak in London, which was traced back to a water pump that pumped from a well contaminated from a cesspit. If a people are pre-germ theory, then this could lead to food taboos such as a ban on raw vegetables, or a belief that ale is healthier than water (due to the boiling required to make mash).
Besdes, heed the words of Michael Westen, from Burn Notice. Bathrooms are a great place to fight. If you’re running a gritty campaign, having a fight take place close to a sewage trench may allow you to up the lethality of a short skirmish via infection. Run a horror campaign, and have some terrifying squirming thing using sewage pipes for transport, like the Flukeman from X-Files.
Start worldbuilding from the commode up, and use all those factors to influence your setting.
