A fluid reservoir (101) includes a number of electrode pairs disposed within the fluid reservoir. Each of the electrode pairs includes a number of sensing electrodes (103), and a number of electrical traces (105) wherein the sensing electrodes are coupled to a respective one of the electrical traces. The fluid reservoir also includes a common electrode (104) electrically coupled to a voltage source (106). A number of properties of a fluid (110) within the fluid reservoir are detected by applying a voltage between the sensing electrodes in an electrode pair, and a level of the fluid within the fluid reservoir is detected by applying a voltage between the electrodes and the common electrode. A multiplexer (102) may be used to selectively couple the sensing electrodes (103) to a processing device (108). The fluid reservoir may be a printing fluid container.