Water Pollution Experiment

Water pollution is something we are all far to aware of. Whether it is plastics in our oceans or substances in our waterways that are invisible to our naked eye, there are many things upsetting the health and balance of our water. In this simple experiment, we explored the impact of a change in pH in water on plants.

Water Pollution Science Experiment

A simple science experiment exploring the effects and damage caused by water pollution on flowers

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Water Pollution Experiment Video

Before we dive into the science behind water pollution and the details of this experiment. Here is a video of us conducting the experiment. If you can’t see the video, please turn off your adblockers. If you are still struggling to see the video, you can also find it on the STEAM Powered Family YouTube Channel.

Before we jump into our water pollution science experiment, let’s explore some water pollution facts and science.

What is Water Pollution?

Water pollution is when water bodies (ponds, wetlands, rivers, stream, canals, oceans) become infected by either visible or invisible pollutants. Pollutants can include garbage, sewage, factory waste, or chemicals such as pesticides or fertilizers. Pollution can also occur due to pH or temperature changes to the water bodies which causes microscopic organisms like bacteria to multiply to harmful levels.

Water pollution is dangerous for our entire ecosystem. Water is essential for life on this planet. If our water becomes unsafe and harmful, it can have devastating consequences.

What Causes Water Pollution?

There are many causes for water pollution including:

  • Industry waste
  • Sewage and wastewater
  • Oil leaks and spills
  • Garbage dumping in water ways
  • Agricultural run off
  • Global warming

What are the Effects of Water Pollution?

Water pollution has a number of negative effects in three main areas.

Health – Poor water quality is a major health issue for humans, animals and plants. According to the UN, ‘every year more people die from unsafe water than from all forms of violence, including war’. This is staggering.

The Environment – Nature has a very delicate balance. All the animal and plant species in an ecosystem rely on each other in order to survive and thrive. Pollution can disrupt the natural balance and relationships between species causing loss and devastation.

Economy – Yes, water pollution costs money. It directly impacts commercial fishing, recreational businesses, tourism and even property values, all of which rely on clean water. 

So now we know how damaging water pollution can be, what can we do about it?

What can we do about Water Pollution?

First, educate yourself on the issues around water pollution by reading, doing experiments and becoming aware of the issues. Awareness is the most important first step. One way to do this, is to participate in World Water Day on March 22 or World Oceans Day on June 8 events in your area.

What else can you do? Here are just a few more ideas.

Reduce any pollution you are putting into our water systems. One popular item discussed around here is glitter. Glitter is often microplastics which can end up in our water systems. Here at STEAM Powered Family we have made a point of using biodegradable glitter for our projects, that is made from plant materials.

Don’t use harmful fertilizers, pesticides and herbicides in your gardens.

Clean up properly after your pets. Human and animal waste is a very common source of water pollution.

Don’t flush medications, trash or other items down the drain that will pollute the water supplies.

Support businesses that commit themselves to protecting our environment and waterways. Money talks and by supporting businesses that are putting our planet first, we can make big changes on a global level.

Support clean water initiatives in your community and around the world.

Water Pollution Experiment

This simple science experiment exploring the effect of water pollution on plants, is focused on changes to the pH of water. Water has a pH of approximately 7, but contaminants in the environment can lower (or acidify) water creating acid rain, which has a pH of approximately 4.

This experiment relies on the plants taking in polluted water. Plants take in water through a process called osmosis.

Osmosis Definition

Osmosis is defined as the movement of a liquid or solvent (such as water) through a semipermeable membrane (as of a living cell) into a solution of higher solute concentration. This tends to equalize the concentrations of solute on the two sides of the membrane.

Osmosis is about finding a natural balance.

In the case of plants, the plant takes in water from the soil through its roots through the process of osmosis. It is then transported through the planet to nourish and sustain it.

But what happens if that water is polluted?

Applying the Scientific Method

This is an excellent experiment to apply the scientific method. The scientific method is a way of approaching an experiment in a systematic way. It involves 7 steps:

  1. Ask a Question – In this experiment our question is: What effect does water pollution have on plants?
  2. Research – We researched water pollution and how plants use water to help us understand the science before starting our experiment.
  3. Develop a Hypothesis – A hypothesis is an educated guess or prediction for what might happen during our experiment. Our hypothesis is that the polluted water will be taken in by the plant, and that water with a low pH will kill the plant.
  4. Experiment – Now we run our experiment. See below for how we did the experiment.
  5. Observe and Evaluate – This is where things got exciting in our experiment. Our observations were very interesting.
  6. Analyze the Results – We spent some time hypothesizing why we got the results we did.
  7. Share the Results – Next we prepared our results to share with all of you!

The Experiment – The Effect of Water Pollution on Plants

For this experiment we needed some simple supplies.

White flowers – we had tulips, but any readily available white flower will work
Jars – Enough for the number of flowers you want to test
White Vinegar
Food coloring


This experiment has two different parts. We decided we wanted to go beyond a simple osmosis experiment, which would demonstrate how plants take in pollutants in water, and see how altered pH in water would affect the plants as well.

Into each jar add the same amount of water. If possible you can use distilled water, but tap water should be fine. As long as your water source is consistent. I added approximately 1/2 cup of water to each jar.

Into all but one jar add a few drops of food coloring. I went with a different color for each jar so we could try and create a rainbow.

In the last jar, add a few drops of white vinegar instead of food coloring.

Cut all your flower stems to the same length and remove any extra leaves if required. You want the flowers to be as identical as possible.

Place one flower in each jar.

Now wait 24 hours.

After 24 hours examine your flowers to see what has happened.

The Results

Osmosis Experiment

Flowers in coloured water jars in an osmosis polluted water experiment

It was interesting to see the white flowers changing colors due to the food coloring. It was a great demonstration on how the pollutants in the water could be seen visibly traveling through the flowers. Even the leaves on some of the flowers started changing from green to the color of the food coloring. This made for an interesting discussion into how this could affect photosynthesis.

Photosythesis is the process used by plants, to use sunlight to synthesize foods from carbon dioxide and water. Photosynthesis relies on the green color of the leaves which is chlorophyll and generates oxygen as a byproduct. So what might happen if pollutants changed the green color? It made for an interesting discussion.

Acidic Water Experiment

Then came the really fascinating part of the experiment. We expected our low pH jar and flower, the one with a big of vinegar added, would wilt and die overnight. It didn’t die. In fact the flower looked fine. What was interesting was how the stem of the flower wilted and curled up.

Close up of the damage to a plant stem in polluted water
Stems in the jar of acidic water

Look at the stems on the left. They took in the food coloring through osmosis, but since the food coloring is not toxic and doesn’t affect pH, it only changed the color of the stems. But the two on the right were in acidic water and their stems shriveled up.

Showing the stems of plants affected by water pollution during an experiment

Here are some close up shots of the stems so you can see the difference.

Close up of stems showing osmosis and pollution from food coloring
food coloring
Close up showing the damage to plant stems from acid rain and polluted water
acidic water

This lead to some fascinating discussions about how this would affect osmosis. And around what was actually happening. Was it a defense mechanism from the plant trying to protect itself from the acidic water? Or was it the cells of the stem breaking down from the acidity? Next time we are planning on making some slides so we can compare the plant cells from the stems of healthy flowers to these damaged stems.

More Environmental Sciences Experiments

If you are doing a unit study on the environment and want more experiment ideas, I highly recommend the following experiments along with this one.

Water Pollution Science Experiment