background
canal
channel
chemical
concrete
conduit
current
danger
dark
dirty
disaster
drain
drainpipe
dump
ecology
environment
fall
fast
filth
filthy
flow
flowing
gray
hole
industrial
industry
mud
nature
outfall
outflow
outlet
pipe
pipeline
pollution
pour
round
rusty
sanitary
sewage
sewer
sewerage
splash
stream
system
tube
tunnel
waste
wastewater
water