Project Grade 9 Engineering & Design
Crestmoor High Water Reuse: A Rainwater and Greywater Design
A grade 9 project where teams design a rainwater and greywater reuse system for a fictional school, sized to a runoff target and held to a fixed budget.
Objectives
- Students will calculate roof runoff and size a storage tank to meet a stated target.
- Students will design a reuse system that fits a fixed budget and defend its trade-offs.
Vocabulary
- Rainwater harvesting
- Collecting rain, usually from a roof, and storing it in barrels or tanks for later use, like watering gardens. It saves treated drinking water for the uses that really need it.
- Greywater
- Gently used water from showers, bathtubs, bathroom sinks, and washing machines. With the right setup, it can be reused to water plants instead of going down the drain.
Also: potable, catchment, storage
Teacher overview
Crestmoor High is a fictional school that pays for clean drinking-quality water even when it flushes toilets and waters the garden. Rainwater from the roof and greywater from sinks could do those jobs instead, cutting the demand for treated water. Over five sessions, teams design a reuse system sized to capture roof runoff and stay within a fixed budget, then present it to the school's facilities board. The final deliverable is a scaled site plan, an itemized cost table, and a short written proposal.
Project Brief
Driving question: How can we design a rainwater and greywater reuse system for Crestmoor High that captures roof runoff, stores enough for dry days, and fits a fixed budget?
Scenario: The facilities board of the fictional Crestmoor High has asked student teams to propose a reuse system. The system will collect rain from the roof and greywater from sinks to flush toilets and water the courtyard garden.
Constraints:
- The roof catchment area is 12,000 square feet. To find runoff, use roof area (sq ft) × rainfall (inches) × 0.623 = gallons. This is the rain that falls on the roof; a real system collects somewhat less.
- The storage tank must hold at least 5,000 gallons so water is available on dry days.
- The materials budget is a fictional $6,000 for the tank, gutters, first-flush diverter, pump, and filter. Teams price parts from the teacher's price sheet.
- Greywater from sinks must run in its own piping, separate from the rain tank. It must be filtered and disinfected before it flushes toilets, must not be stored for more than one day before use, and must not be sprayed on or touch the edible parts of garden plants.
- The design must fit on the courtyard site the teacher provides on grid paper.
Final deliverable: A scaled site plan on grid paper showing the roof, tank, and piping; an itemized cost table at or under $6,000; and a one-page proposal explaining how the design meets the runoff, storage, and budget targets.
Milestones
Session 1 (criteria and constraints): Teams study the scenario and write a short list of measurable criteria and constraints, including the storage target and the budget. They also compute the runoff from one 1-inch storm on the full roof. Output: a criteria-and-constraints sheet with the runoff calculation.
Session 2 (size the system): Teams choose a storage tank that meets the 5,000-gallon minimum and check it against the runoff they found. They decide how much of the toilet and garden demand the stored water can meet. Output: sizing calculations with the chosen tank.
Session 3 (draft the design and cost it): Teams draw a scaled site plan and price every part from the price sheet, keeping the total at or under $6,000. Output: a scaled draft plan with an itemized cost table.
Session 4 (evaluate and refine): Teams check their design against every constraint, list the trade-offs they made, and refine the weakest part. Output: a revised plan with a short trade-off note.
Session 5 (present): Teams present the plan, cost table, and proposal to the class acting as the facilities board, and answer one question from the audience. Output: the final proposal and a short presentation.
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 |
|---|---|---|---|---|
| Runoff and storage sizing | Runoff or storage is missing or wrong | One of the two is found correctly | Runoff is calculated and the tank meets the 5,000-gallon minimum | Sizing is correct and the team explains how storage matches expected demand |
| Budget constraint | Cost is over $6,000 or not itemized | Cost is near $6,000 but not fully itemized | Itemized cost totals $6,000 or less | Itemized cost is under $6,000 with a stated trade-off made to save money |
| Design plan and layout | Plan is unclear or not to scale | Plan is to scale but missing key parts | Scaled plan shows roof, tank, and piping clearly | Scaled plan is clear, complete, and labeled so a builder could follow it |
| Proposal and trade-offs | Proposal is incomplete | Proposal states the design but not the reasoning | Proposal explains how the design meets each target | Proposal explains each target and defends a trade-off against a likely board question |
Differentiation
Support
Give teams the roof runoff already calculated for one storm, so they can focus on tank choice, layout, and budget. Provide a shortened price sheet with fewer part choices to lower the number of decisions.
Extension
Ask teams to estimate how many gallons of drinking-quality water the system would save in a year, using a rainfall total they research and state as an assumption, and to argue whether the savings justify the budget.
ELL supports
Provide a labeled diagram of a rainwater system (roof, gutter, first-flush diverter, tank, pump) before Session 1, and allow the written proposal to use labeled sketches with short sentences rather than full paragraphs.