An exhaust treatment system may include gas, reductant and water conduits, a nozzle and a pump. The gas conduit may be in fluid communication with a source of compressed gas and may include a first valve controlling a flow of compressed gas through the gas conduit. The water conduit may be in fluid communication with a water source and may include a second valve controlling a flow of water through the water conduit. The nozzle may be in fluid communication with the gas, reductant and water conduits. The pump may be disposed between the nozzle and the second valve and may be in fluid communication with the reductant and water conduits. The pump may be operable in a first pumping direction to pump reductant from the reductant source to the nozzle and in a second pumping direction to pump reductant away from the nozzle and toward the reductant source.