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Recycled water and plant growthFeatured science projectScience project video


This science fair project was performed to examine how watering plants with recycled water affects their rate of growth. The experiment involved watering radish plants with distilled water, tap water and recycled water.


Radish plants will grow more quickly when watered with recycled water.

Scientific Terms

Recycled water, nutrients, nitrogen, phosphorus, pathogens, chlorine


Recycled water

Recycled water is basically sewage water that has been treated to remove some of the impurities and solids. Examples are water that is washed down the kitchen sink, flushed down the toilet and water that is used for laundry. Usually, recycled water is used only for irrigation or fire fighting as it is unsuitable for human consumption without being further treated/processed.

The cost of recycled water is normally higher as compared to the cost of acquiring fresh water, in countries where fresh water resources are readily available. However, recycled water is normally sold at a cheaper price to encourage usage, in order to help conserve fresh water resources. Recycled water is also rich in nutrients like nitrogen and phosphorus making it very suitable for use in agriculture and horticulture.
recycled water science fair project

There are some concerns regarding the safety of recycled water and public health. The presence of some pathogens that cannot be destroyed by chlorine, and the possibilities of infecting people as this water is sprayed across lawns or farmland through sprinklers, is cause for concern. Another cause for concern is the seepage of impurities from the recycled water into ground water resources.

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Complexity level:
Project cost ($):
Time required:
1 day to prepare, 28 days for the science project experiment
Material availability:
You will need access to a source of recycled water.
Safety concerns:

Basic safety requirements