canal
chemical
city
collage
contamination
danger
dirt
dirty
discharge
drain
drainage
ecology
environment
factory
flowing
garbage
hazardous
industrial
industry
liquid
nobody
outflow
pipe
poisonous
pollute
polluted
pollution
raw
recycle
river
rubbish
sanitation
set
sewage
sewer
stream
surface
toxic
trash
unhygienic
untreated
urban
waste
wastewater
water
wet