Unit 6. Rainwater Harvesting
After completing Unit 6, students will be able to:
- Describe rainwater harvesting systems in urban areas
- Calculate storage capacity required for rainwater harvesting system
- Apply water balance to determine size and performance of a rainwater harvesting system
Context for Use
Unit 6 requires Unit 5 to have been completed. If the the instructor is not using Unit 5, then results from Unit 5 are provided below for convenience. The primary learning activity of Unit 6 requires the use of an Excel spreadsheet. Students should have laptops or the class needs to be conducted in a computer lab. The expectation is that this unit can be completed in a single 75-minute class session with students completing and submitting the completed spreadsheet, a one-paragraph summary, and a brief response to a discussion question. Pre-class effort requires approximately 1 hour.
Description and Teaching Materials
- Provide Pre-class assignment handout (Microsoft Word 2007 (.docx) 22kB Jul4 16) to students
- Have students read pages 1–9 of the Albuquerque Rainwater Harvesting Manual
- This short reading provides the overview of the basic concepts and terminology of rainwater harvesting.
- Required reading time is approximately 30 minutes.
- View Rainwater Harvesting Video on YouTube, posted by PlumbingGuru.
- Presented by an extension agent in West Texas, this video presents an overview of residential rainwater harvesting.
- Video duration is 13 minutes.
- Discussion questions (enter class with answers ready to submit):
- Describe in five sentences or fewer the difference between simple and complex rainwater harvesting systems.
- Explain why rainwater harvesting is or is not a more sustainable alternative to piped water supply. Provide two reasons.
(15 min) Warm-Up and Discussion of Pre-Class Questions
- Orient students to lesson in module sequence
- Review lesson learning goals
- Instructor-led discussion:
- RWH is an element of decentralized water supply and storm water management
- RWH is a common practice for individuals and local government programs
- Pre-class question 1: simple and complex systems
- Instructor highlights basic components of RWH system
- Pre-class question 2: sustainability
- key considerations: cost, environmental trade-offs, social benefits
(10 min) Cistern Sizing Activity, Part 1: Total Demand Monthly Water Balance
- Instructor reviews cistern sizing student handout (Microsoft Word 2007 (.docx) 23kB Jul4 16) (note: this handout is used in parts 1–3 of this activity), and may use Cistern Sizing PowerPoint slides (PowerPoint 2007 (.pptx) 800kB Sep20 15), which are provided as instructor resource
- Instructor provides explanation of cistern sizing spreadsheet (Excel 2007 (.xlsx) 18kB Sep20 15) (which is also available in a printable format (Excel 2007 (.xlsx) 11kB Sep20 15)).
- Additional instructor resources
- Students work in teams of 3–4; instructor supports teams during exercise
- Instructor facilitates report outs from teams
(20 min) Cistern Sizing Activity, Part 2: Indoor and Outdoor Water Demand Patterns
- Instructor reviews instructions in the cistern sizing student handout (Microsoft Word 2007 (.docx) 23kB Jul4 16) and cistern sizing spreadsheet (Excel 2007 (.xlsx) 18kB Sep20 15) and provides explanation of how to modify spreadsheet
- Student teams carry out task and prepare for report outs
- Instructor supports teams during activity and facilitates report outs
(10 min) Cistern Sizing Activity, Part 3: Individual Reports and Discussion
- Instructor reviews instructions in the cistern sizing student handout (Microsoft Word 2007 (.docx) 23kB Jul4 16)
- Students carry out tasks individually
- Instructor supports individuals during activity and facilitates report outs
(15 min) Revisit Water System Mind Maps
Teams revisit mind maps and add or improve the details describing sustainable water management practices, including rainwater harvesting. Students should consider best practices as well as structural or technological practices. Students should also consider how policies and laws may be connected to rainwater harvesting and other building-related water sustainability practices.
(5 min) Lesson Summary
- Review and check lesson learning goals
- Next class — watershed perspective of sustainable storm water management practices
Teaching Notes and Tips
- Required materials: markers, mind maps, and additional paper for mind map revision activity
- The unit uses spreadsheet tools. Instructors should feel comfortable with their students working with spreadsheets.
- Similar to other units in this module, more depth can follow this overview unit on rainwater harvesting. Instructors could explore cost, payback period, treatment specification, regulations, and more during discussions.
- Pre-class questions submitted for assessment of lesson learning goal #1
- Students each submit a deliverable for the activity that is used for assessment of learning goals #2 and #3
References and Resources
- Virginia Rainwater Harvesting Manual
- Texas Manual on Rainwater Harvesting
- To help comprehend tradeoffs among technical, environmental, and social factors associated with rainwater harvesting systems, see the following paper: Ali, A., Kandiah, V., and Berglund, E. (2014) Multiobjective Optimization to Explore Tradeoffs in Rainwater Harvesting Strategies for Urban Water Sustainability. World Environmental and Water Resources Congress 2014: pp. 1812-1818.doi: 10.1061/9780784413548.180