In North Jersey, N.J., Dirty Water Don dives into a toxic sewer line; In Mt. Vernon, Va., Ramone and George try to fix a sewage-filled basement; In Cleveland, Josh tries to break down a rock-solid formation before it leads to catastrophic flooding.

In Connecticut, Rick searches for a mysterious clog in a treatment plant's outflow pipe; in New York, George and Ramone struggle to clear a clogged reservoir; in Ohio, Josh attends to a backed-up basin that threatens to flood downtown Cleveland.

A Fatberg of wipes, toiletries and trash has formed in a North Jersey sewer pipe; the Cleveland crew find themselves knee-deep in a rain-ravaged storm sewer; Ramon discovers a huge sewer break threatening people's basements in Mount Vernon.

A mysterious clog backs up the entirety of the downtown neighborhood's sewer line; the debris from a severe storm backs up a critical grit chamber; a restaurant grease trap is in dire need of cleaning.

An abandoned sewer line is overwhelmed by stagnant human waste; the damage from a massive sinkhole threatens to shut down the entire city's sewer system; a large clog could take down a city building.

Dirty Water Don repairs outflow gates at a treatment plant; Ramone and George discover medical waste lodged in a pump station; Rick deals with a disgusting grease trap at a meat cutting facility.