Jamieson, Fausset and Brown on Ephesians 5:26

26. sanctify--that is, consecrate her to God. Compare Joh 17:19, meaning, "I devote Myself as a holy sacrifice, that My disciples also may be devoted or consecrated as holy in (through) the truth" [Neander] (He 2:11; 10:10; 13:12 see on He 10:10).

and cleanse--rather, as Greek, "cleansing," without the "and."

with the washing of water--rather as Greek, "with," or "by the laver of the water," namely, the baptismal water. So it ought to be translated in Tit 3:5, the only other passage in the New Testament where it occurs. As the bride passed through a purifying bath before marriage, so the Church (compare Re 21:2). He speaks of baptism according to its high ideal and design, as if the inward grace accompanied the outward rite; hence he asserts of outward baptism whatever is involved in a believing appropriation of the divine truths it symbolizes, and says that Christ, by baptism, has purified the Church [Neander] (1Pe 3:21).

by the word--Greek, "IN the word." To be joined with "cleansing it," or "her." The "word of faith" (Ro 10:8, 9, 17), of which confession is made in baptism, and which carries the real cleansing (Joh 15:3; 17:17) and regenerating power (1Pe 1:23; 3:21) [Alford]. So Augustine [Tract 80, in John], "Take away the word, and what is the water save water? Add the word to the element, and it becomes a sacrament, being itself as it were the visible word." The regenerating efficacy of baptism is conveyed in, and by, the divine word alone.