toxic

pollute

ecological

water

pipe

flow

contamination

river

industrial

waste

ecosystem

chemical

drain

factory

dirty

tube

canal

natural

pollution

fluid

problem

polluted

conservation

flowing

environmental

biology

shore

liquid

pipeline

ecology

unsafe

preservation

cleaning

unhygienic

garbage

dump

sewage

conduit

sewer

outdoors

drainage

nature

environment

plant

background