Thomas M. Lanigan, 84, a retired mechanical engineer with the District of Columbia government who was active in veterans, professional and church groups, died of a heart ailment Saturday at Holy Cross Hospital in Silver Spring.

Mr. Lanigan worked in the city's sanitary engineering department for 34 years before retiring in 1965. He was a life member of the American Society of Professional Engineers and a member of the Water Pollution Control Federation.

A native of Washington, Mr. Lanigan had lived in Silver Spring for the past 38 years. He was a 1915 graduate of McKinley High School and earned a bachelor's degree in mechanical engineering at Catholic University in 1922. He worked for a time on gas and pipe lines in Texas and Louisiana before returning to Washington.

An Army veteran of World ywar I, he was a charter member and past-commander of the Costello Post of the American Legion and in 1977 was post commander of chapter of the Catholic War Veterans of World War I.

Mr. Lanigan was a former member of St. Bernadette's Catholic Church and was a member of St. John The Baptist Catholic Church in Silver Spring at the time of his death. He was a member of the Holy Name Society and had been a member of the Knights of Columbus since 1917. He was a member of the Ancient Order of Hibernians.

Survivors include his wife, Grace M., of Silver Spring; four daughters, Kathleen Louise Lanigan, of Baltimore, and Mary Anne Lanigan, Martha Regina Lanigan and Carole L. Piner, all of Silver Spring; two sons, Thomas M. Jr., of Silver Spring, and John Joseph, of Silver Spring; three sisters, Mary Dooley, Anne Lanigan, and Regina Meehan, all of Washington, and three grandchildren.