Preventative Maintenance Services for the Backflow System at the U.S. Embassy Office, one of the residences and the water treatment systems at 29 Fitzherbert Terrace to be maintained as follows and as... Preventative Maintenance Services for the Backflow System at the U.S. Embassy Office, one of the residences and the water treatment systems at 29 Fitzherbert Terrace to be maintained as follows and as SOW attached. Domestic (Potable) Water Treatment System Booster pumps Water well pump system Water Tank Backflow prevention devices- vendors to be based in New Zealand