Worksheet Grade 10 Health & Consumer Science
Brookhaven's Water Quality Report: A Consumer Science Worksheet
A grade 10 health and consumer science worksheet where students interpret a fictional town's annual water quality report against real EPA regulatory limits.
Objectives
- Interpret a household water quality report by comparing reported readings to real regulatory limits.
- Calculate what percent of a legal limit a reported contaminant level represents.
- Distinguish an action level, a maximum residual disinfectant level, and a secondary standard as different kinds of regulatory benchmarks.
Vocabulary
- Chlorine residual
- Chlorine residual is the small amount of chlorine still left in the water after it leaves the treatment plant. It keeps protecting the water from germs all the way to your faucet.
- Action level
- A trigger number in lead and copper testing. If too many homes test above this level, the utility must take steps like improving treatment and telling the public.
- Turbidity
- Turbidity is a measure of how cloudy or murky water looks because of tiny particles floating in it. Clear water has low turbidity, and muddy water has high turbidity.
Teacher overview
Every US water utility publishes an annual water quality report, sometimes called a consumer confidence report, listing what was actually found in the tap water it delivered that year. This worksheet has students read one fictional town's report and compare its reported readings for chlorine, lead, turbidity, and pH against the real federal benchmarks that apply to each one, since reading this kind of report is a practical skill for any household. A key distinction this worksheet builds is that not every benchmark works the same way: chlorine has a maximum residual disinfectant level, lead has an action level, turbidity has a numeric limit tied to filtration performance, and pH has only a secondary, aesthetic-range standard.
Student Worksheet
Brookhaven is a fictional town invented for this worksheet. Its water utility's most recent annual report lists these readings:
| Contaminant | Brookhaven's reported level | Federal benchmark |
|---|---|---|
| Chlorine residual | 1.1 mg/L | Maximum residual disinfectant level: 4.0 mg/L |
| Lead | 6 ppb | Action level: 15 ppb (dropping to 10 ppb in 2027) |
| Turbidity | 0.18 NTU | Limit: 0.3 NTU in 95% of monthly samples |
| pH | 7.6 | Secondary standard range: 6.5 to 8.5 |
Convert Brookhaven's chlorine residual reading of 1.1 mg/L to parts per million (ppm), using the fact that in fresh water such as tap water, 1 mg/L is approximately equal to 1 ppm.
The maximum residual disinfectant level for chlorine is 4.0 mg/L. What percent of that legal maximum does Brookhaven's reported 1.1 mg/L represent? Round to the nearest whole percent.
Systems typically maintain a chlorine residual between 0.2 and 2.0 mg/L in distribution. Is Brookhaven's 1.1 mg/L reading within this typical range?
Brookhaven's report lists lead at 6 ppb. The current lead action level is 15 ppb. By how many ppb is Brookhaven's reading below the current action level?
In 2027, the lead action level is set to drop to 10 ppb under updated federal rules. Would Brookhaven's 6 ppb reading still fall below this new, stricter action level? By how many ppb?
Explain in one or two sentences why a lead reading can meet today's action level yet still be worth watching closely, given that the action level itself is getting stricter over time.
Brookhaven's turbidity reading is 0.18 NTU. The regulatory limit for a conventional filtration plant's finished water is 0.3 NTU in 95 percent of monthly samples. What percent of that legal limit does Brookhaven's reading represent? Round to the nearest whole percent.
Brookhaven's pH reading is 7.6. The secondary (aesthetic) standard range for drinking water pH is 6.5 to 8.5. Is 7.6 within that range, and is it closer to the low end, the high end, or the middle of the range?
Using your answers above, write one sentence a Brookhaven resident could say to a neighbor, summarizing whether the town's tap water met the federal benchmarks listed in its report this year.
An annual water quality report is published once a year. Explain one advantage and one limitation of judging whether tap water is currently safe to drink using only a single yearly report.
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: 1.1 ppm. Because 1 mg/L is approximately equal to 1 ppm in fresh water (a liter of it weighs about 1 kilogram), a reading of 1.1 mg/L converts directly to about 1.1 ppm. The equality does not hold closely for seawater or brines, which need a density correction.
Answer: 28%. 1.1 ÷ 4.0 = 0.275, which rounds to about 28 percent of the legal maximum.
Answer: Yes. Brookhaven's 1.1 mg/L reading falls between the typical range of 0.2 and 2.0 mg/L that systems maintain in distribution.
Answer: 9 ppb below the current action level. 15 ppb − 6 ppb = 9 ppb.
Answer: 4 ppb below the new 2027 action level. Yes, since 10 ppb − 6 ppb = 4 ppb, so Brookhaven's reading would still fall below the stricter 2027 action level.
Answer: Accept any answer noting that the action level is a regulatory trigger for treatment response rather than a guarantee of complete safety, and that lead has no exposure level considered fully safe for children's developing brains, which is part of why the standard itself keeps getting stricter over time.
Answer: 60%. 0.18 ÷ 0.3 = 0.6, or 60 percent of the legal limit.
Answer: Yes, 7.6 is within the 6.5-to-8.5 range. Since the midpoint of that range is 7.5, a reading of 7.6 sits very close to the middle, just slightly above it.
Answer: Accept any accurate one-sentence summary noting that all four reported readings, chlorine, lead, turbidity, and pH, fell within their federal benchmarks this year (the pH range is a non-enforceable aesthetic guideline, not a legal limit).
Answer: Accept any reasonable answer. A typical advantage: an annual report gives every resident a standardized, publicly available summary, letting them compare their own system to legal limits without paying for private testing. A typical limitation: conditions can change during the year, such as a water-main break or a treatment upset, which an annual report cannot catch until the next reporting cycle.
Differentiation
Support (below grade level)
Provide the percent-calculation setup already written for items 2 and 7 (for example, "1.1 ÷ 4.0 = ___"), and allow a calculator for every computation item. Reduce item 10 to a single required point (advantage or limitation, not both).
Extension (above grade level)
Ask students to calculate, for each of the four contaminants in Brookhaven's report, what percent of its federal benchmark is currently used up, then rank the four from "most room before reaching the limit" to "least room," and explain which single reading they would want to keep watching most closely next year.
ELL supports
Pre-teach "action level," "residual," and "turbidity" with simple definitions and a labeled diagram of a water glass with a scale bar showing where each reading falls relative to its benchmark. Allow items 3, 5, and 8, which ask yes/no comparisons, to be answered with a single word plus a pointing gesture to the relevant table row.