open sewers

Open sewers are drainage channels that carry wastewater and sewage without being enclosed underground—essentially ditches or canals running through streets or alongside buildings.

Common in areas lacking modern sanitation infrastructure, they pose serious health risks from disease and contamination.

Figuratively, calling a place an open sewer suggests it's filthy, corrupt, or morally degraded: The whole department had become an open sewer of bribery and kickbacks.