Worksheet Grade 7 Social Studies & Civics
Millbrook's Water Rate Hearing: A Percent-Increase Worksheet
A grade 7 worksheet on a fictional town's proposed water rate increase, applying multistep percent problems and a common affordability guideline to different households.
Objectives
- Students will calculate the dollar and percent increase of a proposed water rate change.
- Students will apply a household-income affordability guideline to determine whether a bill counts as a high burden.
- Students will explain why a single rate increase affects households differently depending on income.
Vocabulary
Key words: rate increase, affordability, aging infrastructure, public hearing
Teacher overview
Across the United States, a water main breaks roughly every two minutes, a sign of how much of the country's underground pipe network is aging past its expected lifespan, and combined water and sewer bills have risen faster than inflation in recent years, about 24 percent from 2019 to 2024 and about another 5.1 percent in 2025, largely to pay for fixing that same infrastructure. This worksheet places students inside a fictional town's rate-setting decision to make that national pattern concrete. A common misconception this worksheet is built to correct is the idea that a single percentage rate increase costs every household the same amount in a way that matters equally to all of them; because households have different incomes, an identical dollar increase can be barely noticeable to one family and a genuine burden to another.
Student Worksheet
Suppose the fictional town of Millbrook charges every household a flat $40 bill each month for water and sewer service. Millbrook's water main pipes are old. Town engineers say the pipes need major repairs. The town council is holding a public hearing. The council wants to raise the flat bill by 15 percent to pay for the repairs.
What is 15 percent of Millbrook's current $40 monthly bill?
Add that amount to $40. What would Millbrook's new monthly bill be?
A council member proposes a different plan: a flat $50 bill. What percent increase over $40 is that?
Which plan is the bigger percent increase, the one in item 1 or the one in item 3?
Many people use a guideline, or rule of thumb, for water bills. It says water-and-sewer costs above 4.5 percent of a household's yearly income are a high burden. The guideline comes from adding two EPA benchmarks, 2.5 percent for drinking water and 2 percent for wastewater, but EPA itself has no single official cutoff. A Millbrook household earns $24,000 a year. What is the highest monthly bill this household can pay before crossing that guideline? Round to the nearest dollar.
Look at your answer to item 2. Does that new bill go above the guideline amount you found in item 5?
A second Millbrook household earns $8,000 a year. Using the same 4.5 percent guideline, what is this household's highest monthly bill? Round to the nearest dollar.
Look again at your answer to item 2. Does that new bill go above the guideline amount you found in item 7?
Use your answers to items 6 and 8. Explain why one rate increase can be fine for one household and a high burden for another.
Name one group of Millbrook residents who might speak in favor of the rate increase at the public hearing, and one group who might speak against it. Give a reason for each.
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Answer Key
Answer: $6.00.
15% of $40 = 0.15 × 40 = $6.00.Answer: $46.00.
$40 + $6.00 = $46.00, the current bill plus the item 1 increase.Answer: 25 percent.
The increase is $50 − $40 = $10. As a percent of the original: 10 ÷ 40 = 0.25 = 25%.Answer: the flat-$50 proposal.
25% (item 3) is larger than 15% (item 1). Because both plans start from the same $40 bill, the plan with the larger dollar increase, $10 compared with $6, is also the larger percent increase.Answer: $90 per month.
4.5% of $24,000 = 0.045 × 24,000 = $1,080 per year. Dividing by 12 months: 1,080 ÷ 12 = $90 per month.Answer: no.
Millbrook's proposed $46 bill (item 2) is below the $90-per-month guideline (item 5) for a household earning $24,000 a year, so it would not count as a high burden for this household.Answer: $30 per month.
4.5% of $8,000 = 0.045 × 8,000 = $360 per year. Dividing by 12 months: 360 ÷ 12 = $30 per month.Answer: yes.
Millbrook's proposed $46 bill (item 2) is above the $30-per-month guideline (item 7) for a household earning $8,000 a year, so it would count as a high burden for this household.Answer: The same $46 bill is a small share of a higher income and a large share of a lower income, so the guideline in items 5 through 8 shows that a rate increase can be affordable for one household while crossing the high-burden line for another household earning much less.
Answer: Answers will vary. A reasonable pair: a resident whose street has had repeated water main breaks might support the increase because it funds the repair their block needs, while a resident on a fixed income might oppose it because even a modest increase could push their bill above what the household can comfortably afford.
Differentiation
Support (below grade level)
Provide a worked example of the affordability calculation, for a different fictional Millbrook household, fully solved before students attempt items 5 and 7, and allow a calculator for every step. Give sentence starters for item 10: "One resident who might support the increase is ___ because ___."
Extension (above grade level)
Ask students to find the exact household income at which Millbrook's proposed new bill (item 2) equals precisely 4.5 percent of annual income, showing the algebra step by step. Have them explain what that income figure means for the town's hearing debate.
ELL supports
Pre-teach "rate increase," "affordability," and "public hearing" with a simple image of a water bill next to a scale weighing "income" against "bill amount." Allow items 9 and 10 to be answered with short phrases supported by the specific numbers from earlier items, rather than full paragraphs, where the standard permits.