my 25 ft snake didn't clear the last one. i had to rent the 100 ft hose reel on wheels model snake to reach the street.

Hot water, then pure bleach let it sit, then flush with hot water again.

Be careful not to splash yourself with the hot water,.. from the stove to the sink.

Good luck.

What can he do about the sludge? I would be boiling my water if that shit was in my water. Maybe he could find some kind of filter for your water, a heavy-duty filter. Sounds like the city needs to pay for it.

Likely years (maybe decades) of build-up.

when it's unclogged, maybe the smell will go away fast.