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From Your John to the School Lawn: Is Recycled Water Really Safe?

104 reviews


Areas of Science
Time Required
Average (6-10 days)
Material Availability
Readily available
Average ($50 - $100)
Theresa J. Hannig
*Note: For this science project you will need to develop your own experimental procedure. Use the information in the summary tab as a starting place. If you would like to discuss your ideas or need help troubleshooting, use the Ask An Expert forum. Our Experts won't do the work for you, but they will make suggestions and offer guidance if you come to them with specific questions.

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Reclaimed (treated) wastewater can be used for many purposes, including landscape watering and freeing up valuable fresh water for other purposes (like drinking water). It's a great way to conserve water, but is it really safe? This science fair project is designed to find out.


The objective of this science fair project is to investigate if watering with recycled water affects the safety of school lawns.

Experimental Procedure

Before starting this science fair project, you'll need to read about, water quality, water testing, growing grass, and how water is recycled. Once you're familiar with these topics, start your science fair project by growing three patches of lawn in three separate miniature greenhouses. You'll have to decide how to create your greenhouses; one way is to make them out of plastic boxes, chicken wire, and clear plastic trash bags. Water one lawn patch with recycled water, one with distilled water, and the third with tap water. Measure the growth rates of each grass patch and compare their general appearances. Read the guide on Measuring Plant Growth for more ideas on how to evaluate the three lawns. Collect water runoff samples, and using one or more water quality testing kits, test each for pathogens, nutrients, and other characteristics. Water-quality testing kits can be purchased from a variety of science supply stores. See the Approved Supplier Program page for a list of potential vendors.
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Ask an Expert

Do you have specific questions about your science project? Our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Global Connections

The United Nations Sustainable Development Goals (UNSDGs) are a blueprint to achieve a better and more sustainable future for all.

This project explores topics key to Clean Water and Sanitation: Ensure access to water and sanitation for all.
This project explores topics key to Responsible Consumption and Production: Ensure sustainable consumption and production patterns.


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General citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.

MLA Style

Science Buddies Staff. "From Your John to the School Lawn: Is Recycled Water Really Safe?" Science Buddies, 28 July 2017, https://www.sciencebuddies.org/science-fair-projects/project-ideas/EnvEng_p002/environmental-engineering/greywater-for-plants. Accessed 16 Apr. 2024.

APA Style

Science Buddies Staff. (2017, July 28). From Your John to the School Lawn: Is Recycled Water Really Safe? Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/EnvEng_p002/environmental-engineering/greywater-for-plants

Last edit date: 2017-07-28
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