Science Buddies: "Ask an Expert"

I am completing this project from the sciencebuddies website. By accident, instead of using distilled water, I used tap water. How will this affect my results? It's too late to go back and change it. Also, I do not wish to have to do it over. I'm using common bacteria swabbed from a doorknob.

This is the project title from the website:
Do Different Dilutions of Disinfectants Affect the Development of Bacterial Resistance?

Hi!
The best thing to do right now is not to panic! It's great that you caught the fact that you actually used tap water, because tap water is usually not as pure as distilled water, which is why the ScienceBuddies website recommends using distilled water. Usually, scientists use distilled water in order to ensure that the water is free of microorganisms and contaminants that might otherwise be found in tap water. For more information, check out this website:

http://www.ehow.com/about_5079200_diffe ... water.html

Hope this helps!

Hello,

I think it's okay that you used tap water. If you live in the city (e.g. Boston, Chicago, NYC) I think using tap water will be fine. Large cities frequently test their water for traces of anything harmful, so you should be fine. Even if there was something in the water, I'm sure that the effect on your bacteria (if any) will be barely noticeable.

Jane C.