This work describes the first use of a wireless paired emitter detector diode (PEDD) as an optical sensor for water quality monitoring in a lab-on-a-disc device. The microfluidic platform, based on a pH dye/ionogel sensing area combined with a low-cost, wireless optical sensor, PEDD, is applied for monitoring the pH and the degree of turbidity of water samples in real time. Calibration of the system resulted in a linear response that obeys the Beer-Lambert Law. A reasonable correlation between water pH results obtained using the PEDD system and a standard pH-meter was obtained. Copyright © (2011) by the Chemical and Biological Microsystems Society.