In retirement, Kowalski was a resident of Alexandria, Virginia. He continued to work on inventions, and the day before his death he received a patent for a dual-flush toilet system that he designed to conserve water. He died at Walter Reed Army Medical Center on October 11, 1974, after suffering a heart attack while undergoing open heart surgery. He was buried in Arlington National Cemetery.Burial Detail: Kowalski, Frank – ANC Explorer
