The royal-sponsored bathing rite will be held on Wednesday at 5pm at Wat Benjamabophit (Marble Temple).
Sawad received the royal appointment to the Privy Council in 2002 culminating his career in public service.
Following his graduation in structural engineering from the Massachusetts Institute of Technology, he entered the civil service by serving at the Royal Irrigation Department in 1962.
He rose to become director general of the department in 1992, a position he held until his retirement in 1995.
His post-retirement jobs included a judicial appointment to the Supreme Administrative Court from 2000 to 2002.
Born in 1934 into a prominent family in Pattani, he was the seventh son of 10 siblings. He father was civil servant Khunthamrongpanpakdee and his mother was Soithong Wattanayagorn nee Khananurak.
He completed his primary study at a local school. He received his secondary education at Bangkok Christian College before furthering his studies in Australia and the United States.
He is survived by wife Khunying Panjit and a son.