Vacuum Breakers stop the movement of water from the garden hose into the water supply. Water is only supposed to flow in one direction. Clean water flows to faucets. Dirty water from toilets or other drain lines go in one direction away from the clean water. Water flow creates pressure on the flow side. When the water pressure drops, it can create a siphon from your garden hose and send water, potentially dirty water, in your potable water supply. A breaker is installed at the end of your garden hose or hydrant to prevent liquids from being siphoned back into the clean water supply. We carry ASSE 1011 backflow preventers. These hose connection vacuum breakers have been tested at a recognized and listed third party testing lab that confirmed these valves meet the requirements of the American Society of Safety Engineers.