In Zurich (Switzerland), they actually do something similar. A small portion of drinking water passes water fleas/daphnia for quality control. The movement of these fleas is tracked by software. Since these are very active and sensitive, even small impurities are noticeable in the movement pattern. Biomonitoring is everywhere :D,(reply>), we are dependent  on other living creatures,(reply>), I know Austria is also using fleas,(reply>), Actually, they use water fleas to test the well water, but trout to test the lake water! :P