When water flows backward through the water supply system, it is called backsiphonage or backflow. When that water is accidentally mixed with hazardous chemicals or bacteria, it is called dangerous! For this reason, never use spray attachments without a backflow prevention device. The chemicals used on your lawn are toxic and can be fatal if ingested.
A piece of pipe insulation wrapped around a screwdriver handle will give you a better grip when you need more torque, or when the handle is just plain slippery.