Abstract: A water pressure backup device has a water tank mounted between a water source and interior plumbing lines and containing an air bladder that is inflated by a battery powered compressor when water pressure is lost at the source, bladder inflation within the tank thereby providing auxiliary water pressure to the interior plumbing lines. A control unit detects when water pressure at the source is lost, and monitors air pressure in the bladder and water pressure in the tank. When water pressure is restored at the source, the control unit shuts off the compressor and opens an air pressure relief valve at the bladder.