FOLLOWING PREVIOUS PROGRAMS IN WHICH A SIMPLE PISTON PUMP WAS DESIGNED, THIS REPORT IS THE EVALUATION OF THIS SIMPLE PISTON PUMP IN THREE AREAS (THAILAND, NIGERIA, AND BANGLADESH). AS A RESULT OF THESE STUDIES, THESE CONCLUSIONS WERE DRAWN: 1) THE BASIC PUMP CONCEPTS ARE SATISFACTORY. 2) FIVE-EIGHTS-INCH DIAMETER X 1 1/2 INCH LONG BEARING SURFACES ARE MINIMUM AND UNDER EXTREME CONDITIONS, A LARGER SIZE SHOULD BE CONSIDERED. 3) NON-ROTATING PINNED ASSEMBLIES SEEM SATISFACTORY IF USE IS NOT EXTENSIVE AND ACCEPTABLE NUTS AND BOLTS NOT AVAILABLE. 4) A PUMP ROD EXTENSION AND SINGLE UPPER BEARING DOES NOT PROVIDE SATISFACTORY LIFE UNDER VIGOROUS DEEP-WELL PUMPING. 5) BECAUSE OF RISING MATERIAL COSTS, MATERIALS SHORTAGES, AND DIFFICULTIES IN TRANSPORTATION, HAND PUMPS SHOULD BE AS LIGHT AS POSSIBLE WITHOUT JEOPARDIZING PUMP FUNCTION OR LONG LIFE. 6) A PARTICULAR VALVE HAS NOT BEEN PROVEN BETTER THAN ANOTHER; HOWEVER WHATEVER VALVE IS PREFERRED, FABRICATION MUST BE DONE WITH CARE FOR SATISFACTORY OPERATION. 7) THE CHEMISTRY OF THE IRON USED FOR CASTING MUST BE WITHIN AN ACCEPTABLE RANGE TO FACILITATE CASTING AND MAKE AN ACCEPTABLE MANNER WITH THE PRESCRIBED COMPONENTS. BASED ON THE DATA ACCUMULATED, RECOMMENDATIONS ARE GIVEN FOR PUMP CONFIGURATIONS AND MATERIALS OF MANUFACTURE, INCLUDING FABRICATION AND INSTALLATION COMMENTS.