Walter (sometimes erroneously listed as Walten) Banks was born on September 24, 1795 in New York to parents Jonathan and Anna Murphy Banks. As per the 1850 U.S. Census, he was married to Mary Dalton with a daughter (Levina) and a son (David), living in Somers, NY. He cannot possibly be a Civil War veteran (over 60 years old during the war years). His unit, if any, is not known. He is, however, on WPA location 8581 - perhaps because a Civil War marker was found near his grave in the Banks plot (could have been for his son).
As per the 1860 U.S. Census, he was living in Rye, NY and was a carpenter. By the 1880 U.S. Census, he was living in North Castle, NY. He died on August 19, 1882, most likely in North Castle.
He is not on Ancestry.com: 1861-65, nor on Richard Lander's list, or on the NY Data Base, or on the North Castle Town Clerk's list. Sons of the American Revolution Membership Applications, 1889-1970, membership #50541.