Science Buddies: "Ask an Expert"

My son is interested in studying what conditions must be present for microscopic life to appear in water. He is wondering if for example, distilled water, water from the dog’s water bowl, rain water samples are left in different environments (inside, outside, etc.) if microscopic life will appear, and if yes how long it would take. Is this project too difficult for his age level? What magnification level would he need on a microscope to observe microscopic life in water?

Hi Leslie2340,

Welcome to Science Buddies! This is a fascinating topic for a science project. Microbes will grow in distilled water, dog water , and in rain water so your son needs to think of an experiment he can do on the topic. In my experience, bacteria can multiply to levels of 100,000 organisms per ml in distilled water. If there are additional nutrients available, they can grow to higher levels. It usually takes about a month for bacteria to grow to significant levels in something like distilled water. If water has been sitting around for a while, the microbes will already be present.

What problem would he like to solve? With a study on outdoor water, it would also be possible to measure bacterial, algae or protozoan growth.

Here is an abbreviated project idea on building a rainwater collection system. Perhaps you son could investigate the microbial growth in different types of rainwater collectors.

https://www.sciencebuddies.org/science- ... p033.shtml

Here is a link from this website that includes interesting news articles on water microbes. Perhaps your son will be inspired to do a project based on one of these ideas, or perhaps he can find a local news article that would inspire a project.

https://www.sciencebuddies.org/science- ... s+in+water

Does your son have access to a microscope? In that case, I would recommend an algae or protozoan project. If not, then you would need to get Petri dishes and a nutrient medium and do plate counts of bacteria.

Be sure to check out the Science Fair Project Guide on this website; it will guide you through the process of completing the project:

https://www.sciencebuddies.org/science- ... ndex.shtml

Also check the links to Microorganisms safety guide, the Scientific Review Committee, and Microbiology for additional useful information. There are strict rules about working with unknown microorganisms in science projects so your son should check with his teacher for approval before proceeding with any experiments.

https://www.sciencebuddies.org/science- ... nces.shtml

I hope this helps you get started. Please post again if you need advice for a specific idea. Your son just needs to do one carefully controlled experiment with measurable results for his project.

Donna Hardy

Hi Leslie,

This is an interesting project. Depending on what you want to observe (bacteria I am assuming?), you would need a pretty powerful microscope. Bacteria are much smaller than normal cells, and from what I've researched you would need a microscope capable of roughly a 1000X magnification to be able to more clearly see them.

I do see that they sell testing kits for water to check for the presence of coliform bacteria, which are a panel of different types of bacteria:

https://en.wikipedia.org/wiki/Coliform_bacteria

Perhaps using a test might be a simpler way to conduct the experiment. Do you have access to a high-powered microscope?

Let us know and we can help you further,
Pharma