channel
collector
concrete
danger
dark
decay
deep
dirt
dirty
drain
drainage
draining
ecology
environment
factory
flooded
flow
flowing
industrial
inside
interior
leak
leakage
men
mud
mystery
outflow
passage
people
pipe
pipeline
plumbers
pollution
river
round
sewage
sewer
sewerage
sludge
stink
stream
subterranean
toxic
tube
tunnel
underground
waste
wastewater
water
worker