After the war, Bill Costa attended Manhattan College, graduating in 1950 with a degree in civil engineering.

He married Lida Costa that same year, and they soon moved to Yonkers, NY, where they raised a family of three (Barbara, Michael, and William Jr.).

Bill worked for contractors and consultants, designing bridges and roadways, including on the New England Thruway (I-95). While working on the Thruway project, Bill was assigned to the City of New Rochelle, in Westchester, NY, as a consulting engineer.

In 1957, he was hired as New Rochelle's Assistant City Engineer; he eventually became the City Engineer while simultaneously serving as the Commissioner of Public Works until his retirement in 1992.

Bill and Lida still reside in New Rochelle, NY, where he loves to garden and cook.