WATER QUALITY TEST

by Ji-Yeon Chung and Mai Y. Randall

INTRODUCTION

You are an engineer who is responsible for making sure that the city of Troy has water that is drinkable. Not only you have to make sure that the water is drinkable but you also have to make sure that it is in accordance with what the law requires.

One of those requirements is that there are no coliforms present in the water supply. The first question that should pop into your head is "What is a coliform?" Well the definition given by Harold J. Benson, who is the author of Microbiological Applications, is that a coliform is a facultative anaerobe that ferments lactose to produce gas and is a gram-negative, non-spore-forming rod.

The reason you need to know this is because organisms such as Escherichia coli are found in the intestines along with the bad intestinal pathogens and you do not want pathogens in the water that you drink! The pathogens themselves are very difficult to test for. But if there is E. coli in your water source then it is very possible that you have intestinal pathogens. The reason an organism such as E. coli is chosen is because E. coli is not present in soil and water. If E. coli is present in the water sample then you can assume that fecal material has contaminated your water supply. The second question that comes to mind is "How do I test water for coliforms?"

There are three test that are performed to determine the presence of coliforms in water: presumptive test, confirmed test, completed test.

After reviewing all the three steps, we can test for the water that we drink to see if our drinking water is free from the E.coli.