|MadSci Network: Environment & Ecology|
Christine, Your question asks what type of organisms live in drinking water. The answer really depends. Water that is not treated before it is sent to peoples houses can have all sorts of microrganisms in it. Such as bacteria, viruses, protozoans ,worms and algae. Some of these can be seem with a regular microscope. Usually the treatment process removes the larger organisms like the worms , the protozoans and the algae and we won't see them in drinking water. The drinking water in most cities in the United States goes through a process (called treatment) that removes almost all of the micro-organisms that can make us sick. But, it is impossible to get every single cell out of the water. Usually there are still some bacteria left over, even after it is treated. Since there are so few bacteria in drinking water and since they are so small, it is very hard to see them under a regular microscope. Usually, to tell if there are any bacteria in drinking water, we have to try to grow them so there are enough for us to see. We can do this by putting a sample of the water onto a jell-o like substance called agar. If there are any bacteria in the water, they will eat the jell-o and reproduce themselves until there are millions and millions more then in the water. When there are so many, we can see them with just our eyes. We can tell what type of bacteria they are by the diffect colors they make on the agar, and sometimes by using different types of agar. There are many kinds of bacteria that we might find. Water testers usually look for a group called Coliform Bacteria, because some of them can make us sick. Good Luck
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