building
clean
dirty
drink
drop
effluent
element
environment
facility
factory
faucet
filter
filtered
filtering
filtration
icon
illustration
industrial
industry
line
liquid
natural
nature
pipe
pipeline
piping
plant
plumbing
pollution
pump
purification
purified
purity
recycle
sewage
sludge
storage
strainer
supply
symbol
system
tank
tap
trap
treatment
waste
wastewater
water
waterworks