BEND, OR -- Bend home and business owners who have underground irrigation systems need to get the backflow system tested before end-of-season sprinkler system blowouts. D-J Buhman is Safe Drinking Water Coordinator for the City of Bend. He says the tests are the single most critical thing you can do to make sure the water in the home or business is safe and clean.  Buhman says the tests cost between 40-and-80-dollars. He says backflow assemblies that fail must be repaired as soon as possible and retested until they pass.