ON DSCNT TO ZZZ1; PLT OF HS125 RECEIVES FUEL FILTER BYPASS WARNINGS ON BOTH ENGS. DIVERTS TO ZZZ DUE TO SUSPECTED FUEL CONTAMINATION.

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WHILE ON THE ARR PROC N OF WAYPOINT; WE NOTICED 'ENG #1 FUEL' ANNUNCIATOR. WE FLEW THE ACFT AND CONDUCTED THE MANUFACTURER'S CHKLIST. ENG #1 REMAINED AT A REDUCED PWR SETTING WITH ANNUNCIATOR EXTINGUISHED AND NO ENG MALFUNCTIONS. WHILE ESTABLISHED ON THE LOC FOR RWY 6 AT ZZZ1; WE NOTICED 'ENG #2 FUEL' ANNUNCIATOR. WE FLEW THE ACFT AND IMMEDIATELY DECLARED AN EMER TO RECEIVE THE ASSISTANCE OF ATC AND RESCUE/RECOVERY VEHICLES. APCH CTL DIRECTED US TO RWY 4L AT ZZZ. WE MADE AN UNEVENTFUL LNDG ON RWY 4L AT ZZZ. WE MADE THE SAFEST; LOGICAL; EDUCATED; CONSERVATIVE DECISION TO LAND AT ZZZ FOR THE FOLLOWING REASONS: 1) CLOSEST ARPT. 2) LENGTH OF RWY AND ELIMINATION OF LOW ALT CIRCLING PROC. 3) AMOUNT OF SAFETY; RESCUE; RECOVERY VEHICLES. CONTRIBUTING FACTORS (PROB): TAKING A VERBAL AFFIRMATIVE FROM FBO TO THE EFFECT THAT THEIR DISPENSING FUEL HAS BEEN TESTED FOLLOWING HURRICANE. SUGGESTIONS: EDUCATING FBO STAFF ON THE IMPORTANCE OF CLEAN FUEL (ESPECIALLY AVGAS) AND MAKING CREW MEMBERS AN INTEGRAL PART OF THE FBO/TRUCK FUEL SAMPLE TESTING. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE 'FUEL' WARNING ANNUNCIATION IS TRIGGERED BY EITHER EXCESSIVE FUEL TEMP OR A FUEL FILTER BYPASS CONDITION CAUSED BY A BLOCKAGE IN THE FILTER. HE HAD A FUEL SAMPLE AND THE FUEL FILTERS TESTED. THE FINDINGS WERE AN UNACCEPTABLE LEVEL OF RUST IN BOTH. THE LIKELY SOURCE OF THE RUST WAS FROM OXIDIZED STEEL FUEL STORAGE CONTAINERS; EITHER TRUCK TANKS OR UNDERGND FUEL FARM TANKS. THE TESTERS WERE UNABLE TO SPECULATE AS TO A SPECIFIC SOURCE. RPTR ADVISED THAT FLT IN QUESTION ORIGINATED A DAY OR SO AFTER A HURRICANE IMPACTED THE AREA AND HAD BEEN FUELED THERE PRIOR TO DEP.