canal
concrete
conduit
corrosion
drain
drainage
dump
ecology
environment
environmental
factory
floating
flow
flowing
fluid
garbage
generation
gushing
industrial
industry
liquid
mud
old
pipe
pipeline
polluted
polluter
pollution
pouring
river
rust
rusty
sewage
sewer
sewerage
sluice
stagnant
station
stream
substance
toxic
treatment
tube
unclean
waste
waste water
waste water treatment
water
water pipe