What Kinds of Water Yield Fastest Plant Growth?

3.9 based on 64 ratings

Updated on Dec 13, 2013

Grade Level: 5th - 6th; Type: Botany


Students will discover whether distilled water, spring water, or regular tap water yield faster plant growth; in this case, we will use beans. Beans have a fast germination time (2-5 days depending on conditions) so we won't be waiting too long to see results.

Research Questions:

  • What is condensation? What happens during this process?
  • What do plants need to grow?

Plants grow through a process called photosynthesis. This requires sunlight to take place. The chlorophyll located in the chloroplast of the plant cells grabs sunlight and starts the reactions (such as sugar) that are needed to make the plant grow. Water is also needed in the growth equation, because like humans and animals, plants need moisture to quench their thirst.

Tap water is basically just water that comes from indoor plumbing. This water is controlled directly by the water main from the city and runs through a series and network of pipes until it finally reaches the home, of which the faucet is one outlet. This water is treated with chemical compounds and chlorine to kill harmful bacteria, toxins, and other contaminants that cause water-bourne diseases.

Spring water, however, contains natural minerals and as the name suggests, comes from a natural spring and the water comes from beneath the surface of the earth and flows to the surface. Distilled water contains close to none of the minerals nor impurities found in the other 2 types of waters. All of that has been filtered out through the distillation process which involves first boiling water and then allowing the steam to condense.


(from the grocery store/gardening store)

  • 3 beans (i.e. lima beans, lentils, pinto beans)
  • 3 pots with soil
  • distilled water, spring water, and regular tap water

Also required

  • Sunlight
  • Ruler
  • Pen and paper for notes
  • Patience

Experimental Procedure

  1. First we will pot the beans. Use your finger and make a small hole about 2 inches deep into the soil of each of the 3 pots. Put a bean into each hole and cover it up with soil. Give it a pat.
  2. Label each pot with the type of water the plant is going to receive- tap, distilled, or spring.
  3. Take the pots to a windowsill with the same amount of sunlight.
  4. Give the plants their first taste of water. Just give them a little water. Just a sprinkle, spritz, or “rain” would do. Do not overwater them with too much! You will water them the same amount at least daily or when they are dry. You can test if they are getting too much water by just sticking your finger to the side of the bean and into the soil. If your finger comes out muddy, they have too much water and you shouldn't water them. The soil should be a nice dampness or dry.
  5. The beans should germinate in 2-5 days, depending on location and conditions. After this, you should start monitoring their daily growth for 2 weeks and measure how tall the sprout is for each sample. Which one is growing at a faster rate? Is there any difference? Any other things you see like a difference in plant healthiness?
  6. After 2 weeks, analyze your results.

Terms/Concepts: Plant growth process; germination; Photosynthesis; Distillation; Condensation; Water


Jennifer Penn-Chiu is currently a college student with a deep interest in science who is aspiring to become a writer. She writes about all sorts of things across all subjects including, but not limited to; science, crafts, and fashion. She hopes to become a good writer so she can share her thoughts and experiences with the world and future generations.

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