brook
concrete
corrosion
crane
danger
dense
dirty
drain
drainage
drainpipe
drops
environment
environmental
flow
flowing
fluid
garbage
green
industrial
industry
iron
moist
moss
natural
nature
old
outlet
pipe
plant
pollution
rainwater
reflect
river
run
rust
sewage
sewer
sewerage
sparkle
splatter
spray
stormwater
stream
system
torrent
toxic
treatment
tube
waste
water