Watt Watchers of Texas: Texas is Too Good To Waste™

Activity: Calculating Showers

Grade Level:

Activity Overview: Saving water at home is easier than you think. By making small, intentional changes, you can save water at home.

Did you know it takes energy to run water? Water is a precious resource and wasting it not only wastes water but energy too. Reducing water waste saves water, energy, and money. Did you know, heating water alone counts for an average of 15% of total household energy use? 

Conservation is the careful utilization of a natural resource in order to prevent depletion. When we conserve water and are careful about how we use it, we decrease water and energy waste.

Time: Varies based on the activity. A measurement can take place in a single five to fifteen minute activity. Studying consumption will take at least a week to get an accurate picture of water usage.

Materials and Supplies: shower, 5-gallon or 1-gallon bucket, stopwatch/clock, notebook or paper for collecting data

Some of these activities are difficult to complete at school because of the need of a shower. If you do have showers at school, you may want to plan an on-site field trip to do some of these measurements. Otherwise, collect student data from home during class and use your time to compare and contrast across the class.

Activity 1: How Much Water in a Shower?

The purpose of this activity is to calculate the rate of water flowing in the shower in gallons per minute (GPM). Although capped at a federal maximum of 2.5 GPM, different shower heads have different flow rates. Also, adjustable shower heads may have a different flow on different settings. Knowing the GPM for a specific shower is the first step to getting a comprehensive picture of water usage.

Measure the amount of flow through your shower head. If you have a large bucket (5 gallons or more), it may be easier to calculate how many minutes it takes to fill the bucket. If you have a smaller bucket (1 gallon), or multiple smaller buckets, see how many buckets you can fill in one minute.

Use these measurements (and a little bit of math) to calculate gallons per minute.

Activity 2: The Hunt for Hot Water

The variety in home design means that not all dwellings are designed with water heaters in close proximity to showers. Similarly, because of different water heater designs, water is not always hot and readily available for use. However, if the shower is running, water is running whether or not someone is using it.

Wait to perform this test until no hot water has been used anywhere in the house for at least 5 hours. It may be easier to run this test first thing in the morning, just make sure no one has turned any hot water faucets.

Use a stopwatch or clock to measure the amount of time from when you turn the faucet to when the water is hot. Then use the GPM measurement from the first activity to calculate the number of gallons wasted while waiting for the water to get hot.

There will be some discrepancy between when different individuals think the water is hot (completely steaming v. lukewarm). Please be aware that water from only the hot faucet will be hot and can cause scalding. Always use caution around hot water.

Activity 3: More Showers, More Water

Use the stopwatch or clock to calculate how long it takes each family member to shower. You may want to take a measurement every day for a week to get an average length of shower per person for a more representative figure. Then, use the GPM measurement from the first activity to calculate water usage per individual. Compare the figures. Is one person using more water than others or is everyone similar in their consumption habits?

This can also be compared across individual students in a classroom. You may want to consider charting and graphing the results in order to visualize water consumption.

Activity 4: Total Shower Charge

Leverage the usage data from Activity 3 to extrapolate how many gallons per month are used on showers alone. Multiply the average number of gallons used per person times the number of showers per person in a month. The total of everyone's individual usage is the household usage of water for showers alone.

Examine the monthly utility bill. Is there a per gallon charge for water use? Multiply this charge times the total gallon usage for showers each month. This is the total cost of showers in the household. Keep in mind this figure excludes electricity or natural gas to heat the water and any wastewater charge that may be levied for bringing that water away from the dwelling.

Activity 5: Savings are Hot

Go back and review the figures from Activity 2 and Activity 3. Recalculate the potential water usage per individual if water started hot.

First, subtract the amount of time it takes for water to get hot from the number of minutes of each person's average shower time. This is the functional shower time with hot water.

Then, multiply the GPM measurement times the functional shower time to calculate the amount of water used per "ideal" shower.

Rerun Activity 4 with this figure to calculate the monthly water bill without any waste from waiting for hot water. How much could you save?

Installing a cut off valve at the shower head is one way to achieve these savings. Turning the water off at the shower head but calling for hot water from the tank with the main faucet allows the water to reach temperature before flowing into the shower. This small change can lead to significant savings.


SCI.5.2A, SCI.3.2B, SCI.4.2B, SCI.5.2C, SCI.3.2C, SCI.4.2C, SCI.5.2G, SCI.4.2E, SCI.3.4A, SCI.3.4A, SCI.5.4A

MATH.3.1A, MATH.4.1A, MATH.5.1A, MATH.3.2D, MATH.4.2C, MATH.3.4A, MATH.4.4A, MATH.5.3K, MATH.3.4E, MATH.4.4C, MATH.5.3D, MATH.4.8C, MATH.5.7A

Watt Watchers of Texas is a Partner Program of Smart Energy Education.
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