Hobbies And Interests
Types of Water
Collect water samples from different sources, such as ponds or streams, by putting them into small, labeled jars. The labels will help you remember which sample came from which source. For comparison, collect water from sources of treated water, such as water fountains or water taps in public restrooms, as well. A container of distilled water makes a good control group. Dip a sterile swab into each sample and swab a petri dish containing agar, using a new swab and dish for each sample. Blood or soy agar will encourage most bacteria to grow. Label and close the petri dishes as you work so that you do not forget which sample is growing in each dish. Leave the dishes undisturbed for a week. Observe the samples and note which ones contain the most colonies and if the samples seem to contain different types of bacteria. For a variation on this experiment, try testing different brands of bottled water to find out if they are sterile.
Water pH
Grow some bacteria in agar using a kit or by collecting bacteria yourself. Once you have several prepared petri dishes with thriving colonies, mix solutions with varying pH levels. In glasses or glass jars, pour a small amount of distilled water. Add a small amount of vinegar to some of these glasses, in different quantities, and some bleach to others. Bleach is very strong and hazardous, so only use a small amount. Adult assistance may be required. Do not add anything to one glass; this is your control group. Test each glass with a pH test kit. The kind with strips are very easy to use, although there are many simple methods of testing pH. Using a clean eyedropper or pipette, add a small amount of each solution to each petri dish. Label each dish with the pH of the solution that you added. Wait for a few days, then count the colonies and record how the pH of water impacts the growth of bacteria.
Water Temperature
Collect several water samples in small jars from a source known to contain bacteria. Place these jars in different places with similar lighting, putting some jars in some places that are warm and some that are cool. Label each jar so that you do not forget which sample was in each location. Wait for several days. For additional data, use a thermometer to record the temperature in each location several times per day to get an average temperature. Dip a sterile swab into each container and swab a petri dish prepared with agar, using a new swab and dish for each sample. Label the petri dishes so that you remember which sample is being tested. Wait several more days, then observe the petri dishes. Examine the colonies and compare the dishes to each other to determine which temperatures are best for growing bacteria.
Water Treatment
Collect several samples of water known to contain bacteria. Use a different method of water filtration or purification with each. You can try using a water purifier, boiling the water or adding chemicals such as chlorine or iodine. Some methods are more hazardous than others. Feel free to be creative, or test methods that might be urban legends regarding bacteria. Leave one jar untreated to act as a control group, and label all jars with the method used to treat the water. Dip a sterile swab into each sample and swab an agar-treated petri dish that has been labeled to indicate the filtration method used on the sample. Wait for several days, then compare the number of colonies. Fewer colonies indicates a more effective water treatment method. Note which methods seemed most effective, and try to guess why.