A CIESE Collaborative Project

How Much is a Gallon?


Return to Instructions Lesson 1a
How Much in a Gallon?
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NOTE: A one liter container can be substituted for the activity below. Just estimate water usage in liters instead of gallons.

Get a Gallon Container
Bring in a clear plastic gallon container from home or use one provided by your teacher. Fill it up with water.
Make a Guess
Take a good look at the gallon of water. How many gallons do you think you would use to:
  • Wash your hands?
  • Brush your teeth?
  • Take a shower?
  • Take a bath?
  • Flush the toilet?
  • Get a drink?
  • Wash the dishes?
  • Water the lawn?
  • Wash the car?

Running Water
Empty the gallon container of water. Get a stop watch or look at a clock that has a second hand. Turn on a faucet so the water comes out very slowly. Put the empty container under the faucet and at that very same moment start timing. Wait until exactly one minute is up then turn off the faucet. How much water would you guess was in the container? Half? One quarter? Completely full? If the container was completely full, the flow rate of the water would be 1 gallon per minute. If the container was half full, the flow rate of the water would be 0.5 gallons per minute. What would you guess is the flow rate of water for your case?

Empty the container. This time turn on the faucet so that the water is coming out very quickly. Put the container under the faucet and start timing again for exactly one minute. If the first container fills up, quickly move it out of the way and put another empty container under the faucet. After one minute, turn off the faucet. How many containers were filled with water? What would you guess the flow rate of water to be in this case?

Is Flow Rate Important?
Think about the two flow rates that you observed in Step 3. What if you were washing a dirty dish in the sink and it took you 2 minutes to wash the dish.
  • How much water would you use if the water was coming out very slowly (flow rate #1)?
  • How much water would you use if the water was coming out very quickly (flow rate #2)?
  • Do you think flow rate is important for determining how much water is used?

Comparing Gallons and Liters
Here in the U.S. we still use gallons to measure the quantity of many liquids. However, that is starting to change. Can you think of anything that is measured in liters instead of gallons?

If you would like to convert gallons to liters (or liters to gallons), try using one of the conversion calculators in the Reference Material section.