Water treatment

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Across
  1. 2. only contain water molecules
  2. 3. used water
  3. 6. toxic gas
  4. 7. waste water is called...
  5. 8. evaporation then condensation
  6. 9. to remove salt
Down
  1. 1. found in reservoirs
  2. 4. to kill microbes
  3. 5. safe to drink