Three word IBSFA monster creation of the words air, water, and urban.

Although not very common some towns and cities have a proper sewer network and there have been instances where magical items have accidentally been flushed into the sewers with unfortunate results. One example is when a gem-locked air elemental has been flushed down the bog. Many types of air elementals gather up material with their wind powers to form a physical body, and in this case it will gather up a large amount of raw sewerage and literally burst back out of a toilet. Often mistaken as water* elementals and nicknamed "poopmentals" for obvious reasons, these air elementals are often left to dedicated sewerage workers to be brought under control (no adventuring party wants to fight an icky pee monster).



*Water elementals can separate different liquids and can actually draw out pure water from raw sewerage.