At about 15:30 PDT, a Piper PA-23-160 Apache lost an engine and made a forced landing off-airport. The instructor suffered minor injuries and the student pilot was uninjured. The flight was a combination maintenance flight and instructional flight. The instructor said he intentionally failed and secured the right engine but was unable to restart it. He elected to return to the airport but the left engine failed about four miles from the airport. Inspectors found water in the main fuel tanks and in the carburetor bowls of both engines.