A variety of devices can be used for measuring water or wastewater flow where pipes cannot be kept full. Examples include open channel flow (OCF) devices like flumes and weirs in combination with secondary level measurement devices and/or electromagnetic flow (EMF) meter options. Each has its pluses and minuses. However, new proven EMF technology can deliver higher accuracy and the best performance when sized for flow rates at levels above 25 percent filled pipe. It also offers a safer environment, simpler installation, and better measuring performance than other available options.