Worksheet: Water Treatment

In this worksheet, we will practice describing methods of water purification and exploring their advantages, limitations, and common applications.


Potable water must be sterilized before it can be drunk. Which of the following is not a common treatment agent in the production of potable water?

  • AChlorine
  • BOzone
  • CUltraviolet light
  • DCalcium carbonate


Which of the following is not a source of fresh water?

  • AOceans
  • BAquifers
  • CLakes
  • DRivers
  • ERainwater


When preparing potable water from freshwater sources, the water is first passed through a coarse screen. What is the purpose of this screen?

  • ATo help oxygen dissolve in the water
  • BTo neutralize acid in the water
  • CTo catalyze the breakdown of contaminants
  • DTo mix the water thoroughly
  • ETo removed large objects from the water


Which of the following is not a reason why there are more steps in the process of producing potable water from wastewater than from fresh water?

  • AWastewater contains more organic matter.
  • BWastewater contains a lot of dissolved salts and minerals.
  • CWastewater must be treated with stronger detergents and chemicals.
  • DWastewater contains greater amounts of harmful bacteria.
  • EWastewater contains more toxic chemicals.


What usage of water requires the water to be treated by chlorination?

  • AWater for industrial cooling
  • BWater for farming
  • CWater for electricity generation in power plants
  • DWater for drinking
  • EWater for washing clothes


What is the primary goal of the desalination process when producing potable water from saltwater?

  • AKilling bacteria in the saltwater
  • BRemoving fine particles held in suspension in the saltwater
  • CRemoving salts and minerals from the saltwater
  • DRemoving large stones found in the saltwater
  • ERemoving hydrogen ions and neutralizing the saltwater


Why are laboratory solutions usually prepared using pure water instead of tap water?

  • ATap water contains bacteria that may affect chemical reactions.
  • BTap water may contain small particles of dirt.
  • CTap water contains dissolved impurities that may affect chemical reactions.
  • DPure water is slightly acidic, which helps in dissolving ionic compounds.
  • EPure water is cheaper than tap water.


Why is chlorination an essential treatment in the production of potable water?

  • AChlorination removes small particles of dirt.
  • BChlorination ensures the water has a neutral pH.
  • CChlorination improves the taste of the water.
  • DChlorination kills the bacteria in the water.
  • EChlorination removes some types of potassium-based fertilizers.


Which of the following statements does not explain why distillation is a poor method for producing drinking water from seawater in large quantities?

  • ADistillation uses a large amount of energy.
  • BDistillation takes a long time.
  • CLarge scale distillation equipment is expensive.
  • DLarge volumes of seawater must be run through the distillation equipment.
  • EThe large quantities of energy needed are expensive.


When river water is purified, small amounts of fertilizers are often still present in the water after purification. Which of the following statements explains why this is the case?

  • AFertilizers are used at water treatment plants to kill the bacteria in the water.
  • BVery large quantities of fertilizers exist in the untreated river water and it is difficult to remove them all.
  • CThe steps in the purification process do not remove soluble substances.
  • DFertilizers build up in the pipes at water treatment plants and contaminate the treated water.
  • EDistillation does not separate the water from the compounds of the fertilizers.


The water from an underground source is clear when it is brought to the surface from a well, whereas the water from a local river is cloudy. Which of the following statements is true about how both types of water should be treated if they are to be used for drinking water?

Water welling up from the earth
  • ABoth types of water need to be chlorinated, and the water from the river should be filtered.
  • BThe water from the river should be filtered and chlorinated, while the water from the well can be drunk immediately.
  • CBoth types of water need to be filtered and chlorinated.
  • DBoth types of water can be drunk immediately with no treatment.
  • EThe water from the river should be chlorinated, while the water from the well can be drunk immediately.

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