A method for operating a liquid reductant injection system is provided. The method includes storing a reductant mixture of ethanol, water, and urea; drawing the stored mixture into an electrically heated pick-up tube for delivery via a delivery line to the exhaust by operating a pump in a first direction; and, clearing a return line that returns the stored mixture or the delivery line by operating the pump in a second, reverse, direction. In this way, by including ethanol in the reductant solution, a freezing point temperature of the liquid reductant may be reduced.