According to the pilot, due to weather in the local area, he elected to conduct a straight in landing approach, rather than overfly the runway. After slowing the airplane's airspeed, he selected flaps down to 15°, landing gear down, followed by full flaps. The pilot stated that he was distracted by standing water on the runway, and he failed to confirm the landing gear was in the down and locked position. After landing, and realizing that the landing gear was not extended, he checked the landing gear handle which was in the down neutral position with no landing gear indicator lights illuminated. The pilot surmised that upon selection of the landing gear handle on the approach, he must have failed to place the landing gear handle in the full down position. The pilot stated there were no preaccident mechanical malfunctions or anomalies that would have precluded normal operation. In the recommendation section of the NTSB Accident/Incident Reporting Form 6120.1, the pilot stated that the accident may have been prevented if he had followed the airplane's checklist and not allowed the distractions and deviation from routine to alter his normal procedures.