I'm conducting an experiment (for bio) that involves water.?

Well, under any compound microscope found in a lab, you should be able to see any impurities such as dirt or bacteria. If some cannot be seen, you can try to grow a bacteria culture on an agar plate, and place it in an incubator to increase the reproduction rate. That should display all bacteria present. As for acidity, the best thing to do is use litmus paper to indicate if the solution is acidic or basic. And for other ions such as chloride, there are various tests and kits designed for this. Look them up or ask someone in biology, chemistry or biochemistry, they'll know.