Easy, at-home science: The Weight of Water



Freshwater – the kind we use every day – is limited. Even though our world is filled with water, most of it is salt and thus not available as freshwater.  97% of the world’s water is saltwater in the oceans and seas. 2% of the world’s water is frozen or locked deep in the ground. Less than 1% of the world’s water is available as usable freshwater.  With such a limited and important natural resource, conservation is important.


Do you know how much water your family uses in a day? This easy activity builds awareness of water conservation, encourages reuse and recycling, and encourages some out-of-the-[shower stall]-box thinking!  Want to find the answers to our newsletter quiz? Scroll down.


Clean and reuse a gallon milk jug. Fill it with water and weigh it. Each gallon of water weighs around ~8.3 pounds at room temperature. Encourage your children to figure out how much water they use – and waste – every day. Keep a tally of their answers to these simple questions:


– How many times do you brush your teeth? Do you leave the water running or turn it off?
– How many times do you wash your hands?
– How many times per day do you use the toilet?
– How long is your shower every day?


Use these values for average American consumption:

– Old toilets: 4 gallons; New toilets: 1.6 gallons per flush
– Old showerheads: 5 gallons; New showerheads: 2 gallons per minute
– Full bathtub: 36 gallons
– Brushing teeth with water running: 1 gallon
– Leaving the tap running while washing hands or dishes: 1 gallon per minute
– Glasses of water (8 x 8 oz per glass) = 0.5 gallons


Once your children know how much water they use every day, challenge them to figure out the weight of that water! Multiply their daily water usage by 8.3. This is the weight of water they send down the drain everyday.  Children may be surprised to find that they “flush” their own weight in water down the drain every day.  A typical American uses 100 gallons of water per day (that’s 830 pounds of weight!), including the water used to produce food, clothing, furniture, and for transportation. Imagine how much energy it takes to move and clean that much water! Every drop of water that comes into our homes through municipal systems has been treated and pumped, which requires energy – which in many places comes from burning of fossil fuels. Water conservation is also energy conservation!


Want to know more? Use these calculators to see how much water your family uses:

– HomeWaterWorks: Interactive home water usage calculator
– Change the Course Water Footprint Calculator: Comprehensive water and energy footprint calculator
– Water Consumption Calculator: Simple family usage calculator




iSchool incorporates these types of environmentally-conscious activities into our programs. In one hands-on activity about water conservation included in our Family Science Nights, children weighed water and themselves, calculated water usage, made conservation pledges, and created artistic souvenirs to help them remember to conserve. When we are done with the empty water/milk jugs, we turn them into creative jewelry! Want to join the fun? Register for our After-School Programs or Summer Camps!


Answers to our Newsletter Quiz (Subscribe here):


1. TRUE! In a typical day, an American child may directly use 32.5 gallons of water, which weighs almost 270 pounds (32.5 x 8.3 = 269.75)! Assume:

– Shower 1 time for 8 minutes (2 gallons per minutes x 8 minutes) = 16 gallons
– Use the toilet 5 times (1.6 gallons per flush x 5 flushes) = 8 gallons
– Wash hands and/or face 7 times (1 gallon per minute x 7 minutes) = 7 gallons
– Brush teeth with water running = 1 gallon
-Drinking water = 0.5 gallons


2. The average American uses around 80-100 gallons of water per day per capita, considering all uses (direct and indirect).


3. TRUE. According to the USGS: “The industries that produce metals, wood and paper products, chemicals, gasoline and oils, and those invaluable grabber utensils you use to get your ring out of the garbage disposal are major users of water. Probably every manufactured product uses water during some part of the production process.”


4. Less than 1% of the world’s water is available as usable freshwater. It makes sense to conserve the water we need and use every day!


Are you a Wizard of i? How well did you do on the quiz? Let us know on Facebook or Twitter!


Sources: In addition to the calculators listed above, also http://water.usgs.gov/edu/qa-home-percapita.html.