If I wash myself with snow water - If I should make myself as pure as possible, and should become, in my view, perfectly holy. Snow water, it seems, was regarded as especially pure. The whiteness of snow itself perhaps suggested the idea that the water of melted snow was better than other for purification. Washing the hands formerly was an emblem of cleansing from guilt. Hence Pilate, when he gave up the Savior to death, took water and washed his hands before the multitude, and said that he was innocent of his blood; Matthew 27:24. The expression used here by Job, also is imitated by the Psalmist, to denote his innocence:
I will wash mine hands in innocency:
So will I compass thine altar, O Lord. Psalm 26:6.
Verily I have cleansed my heart in vain,
And washed my hands in innocency.
Psalm 73:13.
So in Shakespeare, Richard III:
How fain, like Pilate, would I wash my hands
Of this most grievous, guilty murder done!
And make my hands never so clean - Or, rather, should I cleanse my hands with lye, or alkali. The word בור bôr, means properly purity, cleanliness, pureness; and then it is used to denote that which cleanses, alkali, lye, or vegetable salt. The ancients made use of this, mingled with oil, instead of soap, for the purpose of washing, and also in smelting metals, to make them melt more readily; see the note at Isaiah 1:25. The Chaldee renders it accurately, באהלא - in soap. I have no doubt that this is the sense, and that Job means to say, if he should make use of the purest water and of soap to cleanse himself, still he would be regarded as impure. God would throw him at once into the ditch, and he would be covered with moral filth and defilement again in his sight.

If I wash myself with snow water - Supposed to have a more detergent quality than common water; and it was certainly preferred to common water by the ancients. Of this we find an example in an elegant but licentious author: Tandem ergo discubuimus, pueris Alexandrinis Aquam in manus Nivatam infundentibus, aliisque insequentibus ad pedes - Petr. Satyr., cap. xxxi. "At length we sat down, and had snow water poured on our hands by lads of Alexandria," etc. Mr. Good supposes that there is an allusion here to the ancient rite of washing the hands in token of innocence. See Psalm 26:6 : I will Wash my hands in Innocency; and Psalm 73:13 : Verily I have cleansed my heart in vain, and Washed my Hands in Innocency. And by this ceremony Pilate declared himself innocent of the blood of Christ, Matthew 27:24.

If I wash (y) myself with snow water, and make my hands never so clean;
(y) Though I seem pure in my own eyes, yet all is but corruption before God.

If I wash myself with snow water,.... As it came from heaven, or flowed from the mountains covered with snow, as Lebanon, see Jeremiah 18:14; or was kept in vessels for such use, as being judged the best for such a purpose; so it was used by the ancients (n), as being what whitens the skin, and strengthens the parts by contracting the pores, and hindering perspiration; it signifies, in a figurative sense, that let him take what methods he would to cleanse himself from sin, they were all in vain, his iniquity would be seen, and remain marked before God; and indeed there is nothing that a man can do that will make him pure and clean in the sight of an holy God; this is not to be done by ceremonial ablutions, such as might be in use in Job's time, before the law of Moses was given, and to which he may have some reference; these only sanctified to the purifying of the flesh, or only externally, but could not purify the heart, so as to have no more conscience of sin; nor by moral duties, not by repentance, as Sephorno; a fountain, a flood, an ocean of tears of humiliation and repentance, would not wash away sin; if, instead of ten thousand rivers of oil, so many rivers of brinish tears could be produced, they would be of no avail to cleanse the sinner; nor any works of righteousness done by man, for these themselves need washing in the blood of the Lamb; for nothing short of the blood of Christ, and the grace of God, can do it:
and make my hands never so clean; the hands are what men work with, Ecclesiastes 9:10; and so may design good works, which are sometimes called clean hands; see Psalm 24:4; compared with Psalm 15:1; and may be said to be so when they are done well, from a pare heart, and faith unfeigned, without selfish and sordid views, with a single eye to the glory of God; which is doing them as well, and making the hands as clean, as well can be; yet these are of no avail with respect to justification before God, and acceptance with him, or with regard to salvation, which is all of grace, and not of works, be they what they will; some render the words, "and cleanse my hands with soap" (o), which cleanses them best of anything, see Jeremiah 2:22.
(n) "Discubuimus, pueris aquam nivalem in manus infundentibus", Petronius in Satyr. (o) Smegmate, Codurcus, Junius & Tremellius, Piscator, Schmidt; so the Targum, and Mr. Broughton.

snow water--thought to be more cleansing than common water, owing to the whiteness of snow (Psalm 51:7; Isaiah 1:18).
never so clean--Better, to answer to the parallelism of the first clause which expresses the cleansing material, "lye:" the Arabs used alkali mixed with oil, as soap (Psalm 73:13; Jeremiah 2:22).

If - If I clear myself from all imputations, and fully prove my innocency before men.