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Worksheet Grade 10 Health & Consumer Science

How Much Does Bottled Water Really Cost the Ramos Family?

A grade 10 consumer worksheet comparing the per-gallon and yearly cost of bottled versus tap water for a fictional family, with two conservation calculations.

Objectives

  1. Students will calculate and compare the per-gallon cost of bottled and tap water.
  2. Students will estimate a family's yearly savings from choosing tap over bottled water.

Vocabulary

Flow rate
Flow rate measures how much water moves past a point in a certain amount of time, like gallons per minute through a garden hose. Bigger pipes and stronger pushes give bigger flow rates.

Also: cost per gallon, unit price, conservation

Teacher overview

Bottled water feels cheap by the bottle, yet the same water from the tap costs a tiny fraction as much per gallon. This worksheet follows the fictional Ramos family as they compare what they spend on bottled drinking and cooking water with what the same amount would cost from their tap, then looks at two simple conservation choices. It builds the habit of comparing prices by the gallon rather than by the container.

How Much Does Bottled Water Really Cost the Ramos Family? — Grade 10 Health & Consumer Science
Name: ____________________________ Date: ______________

Student Worksheet

Use the figures below for the fictional Ramos family in the town of Alder Creek. These numbers are invented for this exercise.

  • Bottled water costs $1.15 per gallon.
  • Tap water from Alder Creek Water costs $5.00 per 1,000 gallons.
  • The family uses 2.5 gallons of drinking and cooking water per day.
  • Use 365 days in a year.
  1. What is the cost of one day of drinking and cooking water if the family buys it bottled, at 2.5 gallons times $1.15 per gallon?
  2. How many gallons of drinking and cooking water does the family use in one year, at 2.5 gallons per day?
  3. What is the cost of one year of bottled drinking and cooking water for that many gallons, at $1.15 per gallon?
  4. Tap water costs $5.00 per 1,000 gallons. What is the tap-water cost of a single gallon, in dollars?
  5. What would the same yearly amount of water cost from the tap, using your gallons from item 2 and your per-gallon tap price from item 4?
  6. About how much would the family save in one year by drinking tap instead of bottled water? Explain whether cost per gallon or cost per year makes the difference easier to see.
  7. Bottled water is about how many times more expensive per gallon than tap water here? Divide the bottled price by the tap per-gallon price.
  8. Explain in one or two sentences why comparing price per gallon is more useful than comparing the price of one bottle to another.
  9. The family's whole household averages about 300 gallons of water per day. What percent of that daily total is the 2.5 gallons used for drinking and cooking?
  10. Replacing a 2.5 gpm showerhead with a 2.0 gpm model saves 0.5 gallon each minute. How many gallons would that save during one 8-minute shower?

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key

All dollar figures below refer to the fictional Ramos family scenario.

  1. Answer: $2.88.
    One day bottled is 2.5 gallons x $1.15 = $2.875, which rounds to $2.88.
  2. Answer: 912.5 gallons.
    At 2.5 gallons per day for 365 days: 2.5 x 365 = 912.5 gallons.
  3. Answer: $1,049.38.
    Bottled cost for the year is 912.5 gallons x $1.15 = $1,049.375, or about $1,049.38.
  4. Answer: $0.005 per gallon.
    Tap costs $5.00 per 1,000 gallons, so one gallon is $5.00 / 1,000 = $0.005.
  5. Answer: $4.56.
    The same 912.5 gallons from the tap: 912.5 x $0.005 = $4.5625, about $4.56.
  6. Answer: about $1,045.
    Yearly savings is roughly $1,049.38 - $4.56 = $1,044.82. Cost per year makes the gap easier to feel, while cost per gallon makes the price difference clearer; either supports the same conclusion.
  7. Answer: 230 times.
    Divide the prices per gallon: $1.15 / $0.005 = 230, so bottled is about 230 times more expensive per gallon.
  8. Answer: Per-gallon pricing lets you compare fairly.
    Bottles come in different sizes, so comparing per gallon puts every option on the same scale and reveals the true unit price, which a single bottle's price hides.
  9. Answer: about 0.83 percent.
    The share is 2.5 / 300 x 100 = 0.833, about 0.83 percent, showing drinking and cooking water is a very small slice of total household use.
  10. Answer: 4 gallons.
    Saving 0.5 gallon per minute over 8 minutes: 0.5 x 8 = 4 gallons saved per shower.

Differentiation

Support

Provide a filled-in unit-price row for a worked third example (a beverage at a known price per gallon) so students see the division pattern before item 4. Allow a calculator and give the rounding rule that money is reported to the nearest cent.

Extension

Ask students to find the number of days it would take the bottled-water habit to cost as much as a fictional $220 reverse-osmosis system, using the daily bottled cost from item 1, and to interpret the result.

ELL supports

Pre-teach "per gallon," "unit price," and "savings" with a simple picture of a large jug labeled by the gallon next to small bottles. Allow items 6 and 8 to be answered with short phrases or a labeled comparison.