Project Grade 10 Health & Consumer Science
Linden Terrace Apartments: A Legionella Water Safety Plan
Teams rank Legionella risks in a fictional senior apartment building from its water log, plan flushing and temperature checks, and write a notice for residents.
Objectives
- Students will explain how Legionella bacteria grow in building water systems and how people are exposed, and identify who is at higher risk of Legionnaires' disease.
- Students will rank locations in a building by Legionella risk using a water log, and build a control plan that fits stated limits on staff time and money.
- Students will judge whether a one-sample test report supports a conclusion about a whole building.
- Students will write a resident health notice that is accurate, readable for older adults, and states what residents should do.
Vocabulary
Key words: Legionella, Legionnaires' disease, aerosol, stagnation, biofilm, flushing, scald, water management plan
Teacher overview
Legionnaires' disease is a serious lung infection caused by Legionella bacteria. The bacteria live naturally in lakes and streams at low levels, yet outbreaks are usually traced to building water systems: water heaters set too low, pipes where water sits unused, showerheads, spas, and decorative fountains. People become infected by breathing in fine mist that carries the bacteria rather than by drinking tap water in the ordinary way, and older adults are among the groups at highest risk. In this five-session project, teams act as advisers to Linden Terrace, a fictional apartment building for older adults in the fictional town of Stowhurst. Working from the building's water log, a price list, and a weekly limit on staff time, teams rank where the risk is, write a control plan, evaluate a testing company's report, and write a health notice for residents, then present all of it to the building's residents' council.
Teaching note: a common misconception is that Legionella is a drinking-water problem that a pitcher filter or bottled water would solve. The route of exposure is inhaled mist, so the showers, the spa, and the fountain matter far more than the kitchen tap, and students who rank the kitchen sink as the top risk have missed the central idea. A second misconception is that hotter water is always the safer choice. Hot water controls Legionella, yet water hot enough to do that can scald an older adult within seconds, so the building has to manage both risks at once; the price list includes anti-scald mixing valves for that reason. The temperature targets, prices, and staff times in the brief were set for this scenario. Real buildings set their own targets in a water management program that follows public health guidance, and a local health department sanitarian or a building facilities manager makes a good guest for the final session.
Project Brief
Driving question: Where could Legionella grow in the Linden Terrace water system, and what plan would lower the risk to residents within the building's limits on money and staff time?
The client. Linden Terrace is a fictional four-story building for older adults. It has 24 apartments, a lobby with a decorative fountain and a small kitchen, and a fitness room with a warm-water spa that some residents use to ease stiff joints. The building manager has asked your team to draft the building's first water management plan and to present it to the residents' council.
What you need to know about Legionella
- Legionella bacteria live in lakes and streams in small numbers. They become a problem when they grow inside a building's pipes and fixtures.
- They grow best in water that is warm but not hot. They also grow where water sits still, and where the disinfectant from the town's water has faded away.
- They live in biofilm, the thin slime that forms on the inside of pipes, tanks, and showerheads. Rust and scale give biofilm more places to hold on.
- People get sick by breathing in tiny drops of mist that carry the bacteria. Showers, spas, and fountains all make that kind of mist. Drinking water in the normal way does not usually make people sick, and the disease does not usually spread from one person to another.
- Legionnaires' disease is a type of pneumonia. Signs include cough, fever, chills, muscle aches, headache, and shortness of breath. Doctors treat it with antibiotics, and it is most dangerous when treatment starts late.
- People at higher risk include older adults, people who smoke or used to smoke, people with long-term lung disease, and people whose immune systems are weakened by illness or medicine.
- Buildings control Legionella by keeping hot water hot, keeping cold water cold, keeping water moving, keeping disinfectant in the water, and cleaning fixtures.
- Very hot water can scald skin, and older adults burn more easily. An anti-scald mixing valve blends hot and cold water at the shower. It lets a building store water hot while it reaches the resident at a safe temperature.
The draft targets. These targets were set for this project. Water leaving the water heater should be 140°F or hotter. Hot water at any tap should reach at least 120°F after running for one minute. Cold water at any tap should be 75°F or cooler after running for one minute.
The building's water log. The part-time maintenance worker took these readings last week.
| Location | How it is used | Readings | Worker's notes |
|---|---|---|---|
| Water heater outlet, basement | Heats water for the whole building | 128°F | Setting was turned down last winter to lower the gas bill |
| Apartment 104, first floor | Occupied; shower used daily | Hot 121°F, cold 64°F | No problems reported |
| Apartment 212, second floor | Empty since spring | Hot 96°F, cold 78°F | Water ran rusty brown at first, then cleared |
| Apartment 318, third floor | Resident away for two months | Hot 104°F, cold 76°F | White scale inside the showerhead |
| Apartment 407, fourth floor | Occupied; last apartment on the hot-water line | Hot 109°F, cold 71°F | Resident says the hot water "takes forever" to warm up |
| Lobby fountain | Decorative; sprays all day | Water 79°F | Recirculates the same water; cleaned when it looks dirty |
| Fitness room spa | Used by about ten residents a week | Water 102°F | Disinfectant checked once a week |
| Lobby kitchen sink | Staff coffee station; used daily | Hot 124°F, cold 62°F | No problems reported |
The testing company's report. Last month a fictional testing company took one sample of cold water from the lobby kitchen sink. The lab found no Legionella in it. The company's summary reads: "Building water tested negative for Legionella. No further action needed."
Price list for one-time fixes. All prices are fictional and were set for this project. Your total budget is $2,500. Twelve of the 24 apartments already have anti-scald valves from a past remodel, and the other twelve do not.
| Fix | Cost |
|---|---|
| Raise the water heater setting to 140°F | $0 |
| Anti-scald mixing valve installed at one shower | $150 each |
| Drain, clean, and shut off the lobby fountain for good | $0 |
| Replace the fountain with a plant display | $300 |
| Automatic disinfectant feeder and test kit for the spa | $1,200 |
| Close the spa for good | $0 |
| New showerhead that comes apart for cleaning | $25 each |
| Legionella test of one water sample at a certified lab | $90 per sample |
Staff time list. The maintenance worker has 180 minutes each week for water tasks. These times were set for this project.
| Weekly task | Time |
|---|---|
| Flush every tap and the shower in one unused apartment | 15 minutes |
| Check and record the temperature at one location | 5 minutes |
| Test and record the spa's disinfectant level | 5 minutes per check |
| Clean and soak one showerhead | 20 minutes |
| Clean the lobby fountain basin | 45 minutes |
What your team turns in
- A risk map. Color each location from the log on the floor plan as high, medium, or low risk. Write one sentence for each location that names the growth conditions, the mist, and the people exposed.
- A water management plan of two to three pages. It must give a control step for every high-risk location, a weekly task schedule with its minutes added up, a list of fixes with its cost added up, and a reason for each fix. It must also explain how the plan prevents scalds while keeping hot water hot.
- One paragraph that evaluates the testing company's report.
- A one-page health notice for residents in large print and plain words. It must explain the risk, what the building is doing, what residents should do, and when to call a doctor.
- A presentation of no more than eight minutes to the residents' council.
Milestones
Session 1: Learn the health risk. Read the brief as a team. Build a chart with three columns: what helps Legionella grow, how people are exposed, and who is at higher risk. Under each column, list the log locations that fit. Output: the completed three-column chart and a list of questions for the building manager.
Session 2: Rank the risks. Compare every reading in the log with the draft targets. Rank each location as high, medium, or low risk by weighing three things: conditions for growth, whether it makes mist people breathe, and who uses it. Color the floor plan and write the reason sentences. Output: the finished risk map.
Session 3: Build the plan and check the report. Choose a control step for each high-risk location. Build the weekly schedule and show that its minutes add up to 180 or less. Choose fixes from the price list and show that their cost adds up to $2,500 or less. If you raise the heater setting, explain how every resident's shower will be kept safe from scalds. Then write one paragraph on the testing company's report: what was sampled, what was not, and whether one negative result supports "no further action needed." Output: the draft plan with its time and cost totals, and the report paragraph.
Session 4: Write the resident notice. Draft the one-page notice. Trade drafts with another team and check them against three tests. Every health statement must match the brief. Each sentence must be short enough to read at a glance. The notice must tell residents exactly what to do when they come home after being away. Revise your notice using the feedback. Output: the final notice.
Session 5: Present to the residents' council. Present the risk map, the plan, the report paragraph, and the notice. Classmates play council members and ask at least two questions, such as why the spa stays open or closes, or why the fountain has to change. Answer with evidence from the log. Output: the presentation and the full team packet.
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Rubric
| Criterion | Emerging | Developing | Proficient | Advanced |
|---|---|---|---|---|
| Risk map and health reasoning | Ranks locations without reasons, or ranks the kitchen sink as the top risk because people drink from it | Gives reasons based on temperature alone and does not consider mist or who is exposed | Ranks every location using growth conditions, mist, and the people exposed, and places the heater, the unused apartments, the far apartment, the spa, and the fountain above the used taps | Does everything at the proficient level and explains how one problem, such as the low heater setting, raises the risk at several other locations |
| Control plan within the limits | Plan is missing control steps for some high-risk locations, or its time or cost total is over the limit | Plan covers the high-risk locations, but the schedule or budget is not added up or does not fit | Plan covers every high-risk location, its weekly minutes total 180 or less, its cost totals $2,500 or less, and it explains how scalds are prevented | Plan meets every limit and names a trade-off it made, such as closing the spa or leaving some valves for next year, with a health reason for the choice |
| Evaluation of the test report | Accepts the report's conclusion or rejects it without a reason | Notes one weakness, such as the single sample, without linking it to the conclusion | Explains that one cold-water sample from a busy tap cannot show the whole building is safe, and names locations that should have been sampled | Does everything at the proficient level and explains that even a well-chosen negative sample shows conditions at one time and place, while the log shows conditions that let Legionella grow |
| Resident health notice | Notice has health errors or does not tell residents what to do | Notice is accurate but long, crowded, or missing the steps to take after being away | Notice is accurate, in large print and short sentences, and covers the risk, the building's actions, what to do after being away, and warning signs to report to a doctor | Notice meets the proficient level and is organized so a reader can find each action at a glance, with headings or numbered steps that a trade-draft reader confirmed were clear |
| Presentation | Presentation skips parts of the packet or cannot answer questions | Presentation covers the packet but answers questions without evidence | Presentation covers all four products within eight minutes and answers questions with evidence from the log | Presentation does all of that and anticipates a likely resident concern, such as losing the spa or the fountain, before it is raised |
Scoring reference for the teacher. High-risk locations in the log are the water heater outlet (below its target, which lowers hot water temperatures throughout the building), apartment 212 (months of stagnant water at 96°F with rust, which suggests sediment and biofilm), apartment 318 (weeks unused, warm hot water, and scale in the showerhead, with a resident who will shower on return), apartment 407 (occupied, with hot water at 109°F in the growth range at every shower), the spa (warm water, heavy mist from the jets, and disinfectant checked only weekly), and the fountain (warm recirculating water that sprays mist in a room everyone walks through). Apartment 104 and the kitchen sink are low risk because they meet the targets and are used daily; accept a medium ranking for either if the team gives a reason. One plan that fits the limits flushes apartments 212 and 318 twice a week (4 × 15 = 60 minutes), tests the spa twice a day (14 × 5 = 70 minutes), checks temperatures at the heater and apartment 407 twice a week (4 × 5 = 20 minutes), and cleans one showerhead a week in rotation (20 minutes), for 170 minutes. Its fixes are twelve mixing valves (12 × $150 = $1,800), which allow the heater to go back to 140°F, the plant display in place of the fountain ($300), three new showerheads for apartments 212, 318, and 407 (3 × $25 = $75), and three follow-up lab samples from apartment 212, apartment 407, and the spa (3 × $90 = $270), for a fictional total of $2,445. Strong teams using this approach also notice that the lobby kitchen sink has no mixing valve and add a hot-water caution sign there once the heater setting goes up. Accept other plans that meet both limits and give health reasons. A strong notice tells residents to let staff know before they return from being away so the apartment can be flushed, or, if they flush it themselves, to run the hot and cold water in the shower and at every tap until the hot water is fully hot and the cold water is fully cold, stepping out of the bathroom while the shower runs so they do not breathe the mist. It also tells them to call a doctor promptly about cough, fever, or shortness of breath and mention any recent spa use.
Differentiation
Support
Give teams a partly completed three-column chart for Session 1 with two locations already placed, and a planning table for Session 3 that lists each high-risk location with blank cells for the control step, minutes, and cost. Provide a notice template with four headings (What is happening, What we are doing, What you should do, When to call a doctor) so teams can focus on accurate content and plain wording.
Extension
Ask teams to write a one-page memo to the building owner explaining what the fictional budget could not cover this year and what they would ask for next year, such as a plumber's review of why hot water reaches apartment 407 so slowly. Teams can also draft a sampling plan for the certified lab that says which outlets to test, whether to sample hot or cold water, and when, with a reason for each choice.
ELL supports
Pre-teach "stagnant," "biofilm," "mist," "scald," and "flush" with a labeled drawing of a bathroom that shows the showerhead, the mixing valve, and the mist in the air. Allow teams to draft the resident notice in the home language first and then in English, and offer sentence frames for the risk map such as "This location is high risk because the water is __ and people breathe mist when __."
Extensions
Students can compare the Linden Terrace plan with the needs of another building type, such as a hotel, a hospital wing, or their own school's locker rooms, and explain which parts of the plan would change for that building and why. A local health department's environmental health staff can be invited to explain how they respond when a case of Legionnaires' disease is reported and how they trace it to a building.