Water for Schools
Menu

Lesson plan Grade 7 Health & Consumer Science

What Cottonmill Households Do During a Boil-Water Advisory

A grade 7 water-safety lesson in which students read a fictional boil-water notice and build a step-by-step flowchart of the actions a household should take.

Objectives

  1. Students will explain why a pressure loss can trigger a boil-water advisory.
  2. Students will translate a written advisory into an ordered flowchart of household actions.
  3. Students will decide which household tasks need boiled or bottled water and which do not.

Vocabulary

Backflow
Backflow is water flowing backward through a pipe in the wrong direction, which can pull dirty water into the clean drinking water system. Special devices are installed on pipes to stop it.
Distribution system
A distribution system is the network of pipes, pumps, valves, and storage tanks that carries treated water from a treatment plant to homes, schools, and businesses. Most of it is buried underground beneath streets.

Also: advisory, pressure

Teacher overview

A boil-water advisory is a public-health message a utility sends when it cannot guarantee that tap water is free of harmful microbes. This lesson gives students a fictional advisory from the Cottonmill Water District, issued after a water main break, and asks them to turn its dense wording into a clear flowchart a household could follow. Reading the notice alongside a visual they build themselves is the point: a real advisory lists many instructions at once, and organizing them into ordered steps is a practical consumer-safety skill.

Procedure

Hook (5 min): Ask students what they would do if a message from the water utility told them not to drink the tap water. Collect a few reactions. Explain that these messages, called boil-water advisories, follow a predictable structure, and that today the class will decode one from the fictional Cottonmill Water District.

Read the advisory (10 min): Distribute the sample notice. It states that a water main broke overnight, that pressure in part of the system dropped below the minimum, and that residents in the affected area should boil tap water before drinking or cooking until further notice. Have students read it once silently, then underline every instruction they can find.

Direct instruction (8 min): Explain the reason behind the advisory. Distribution systems normally run at 40 to 80 psi, and most states require at least 20 psi at every connection so that clean water pushes outward and nothing can seep in. When a main breaks and pressure falls below that minimum, outside water and bacteria can be pulled into the pipes through the break, or water can flow backward into the system through a hose or other cross-connection, a problem called backflow. Boiling water for one minute kills the microbes that might have entered.

Build the action flowchart (15 min): In pairs, students convert the advisory into an ordered flowchart with three branches: water for drinking and cooking (boil one minute, then cool), water for brushing teeth and making ice (use boiled or bottled), and water for tasks that do not touch the mouth, such as flushing toilets or washing hands with soap (tap water is fine). As a formative check, circulate and confirm each pair has correctly sorted at least six household tasks into the right branch before the debrief. When the flowchart is done, pairs answer the four check questions in the Student Handout.

Closure / debrief (7 min): Bring the class together. Ask: "The advisory is lifted two days later. What should a household do before drinking straight from the tap again?" Guide students to the answer that they should run the cold tap for several minutes to clear old water from the pipes, then resume normal use.

What Cottonmill Households Do During a Boil-Water Advisory — Grade 7 Health & Consumer Science
Name: ____________________________ Date: ______________

Student Handout

Check questions:

  1. Why did the Cottonmill Water District issue the advisory?
  2. What is backflow?
  3. Which household tasks need boiled or bottled water, and which can use tap water?
  4. How should drinking water be prepared during the advisory?

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

Answer Key
  1. Answer: A water main broke and system pressure dropped below the safe minimum, so bacteria could enter the pipes through the low-pressure gap.
  2. Answer: Backflow is when water flows backward into the drinking-water pipes, for example through a hose or other cross-connection, because pressure in the main has fallen too low; it can carry contaminants into the system.
  3. Answer: Drinking, cooking, brushing teeth, and making ice all need boiled or bottled water; flushing toilets and washing hands with soap can use tap water.
  4. Answer: Boil the water for one minute and let it cool before drinking, which kills microbes that may have entered during the low-pressure period.
  5. Debrief answer: After the advisory is lifted, run the cold tap for several minutes to flush old water from the household pipes before drinking directly again.

Differentiation

Support

Provide a flowchart template with the three branch headings already written, so students place the tasks rather than design the structure. Offer a word bank of household tasks to sort.

Extension

Ask students to write the two-sentence text message the utility should send when the advisory is lifted, including the flushing step, in plain language a family could act on immediately.

ELL supports

Pre-teach "advisory," "boil," "backflow," and "pressure" with simple icons. Allow students to complete the flowchart using pictures or single words rather than full sentences, and pair them with a partner for the reading step.