black hole
body
chlorine content
clean
cleaning
consumption
drain
drink
event horizon
food
gravitation
h2o
hole
household
household cleaning
hydrogen
hygiene
kitchen
kitchen sink
liquid
massive
metal
metallic
metaphor
nirvana
oxygen
pollution
potable
purification
purity
resource
rinse
singularity
sink
space
star
state of aggregation
swirl
transparent
wash
washing
water
water consumption
wet