Leviticus 15:11

And whoever toucheth him who hath the issue, and washeth not his hands in water, shall be unclean; if he be a man, he shall wash his clothes, and bathe in forty seahs of water, and be unclean until the evening.

if he did not rinse his hands in water It would appear that if a man suffering a flow were to touch food (or any other object) with hands that had been rinsed, then the object should not become ritually impure, since it did not touch the area of the flow. However, we know [Torat Kohanim on this verse] that our ancestors all understood “hands” here to represent the entire body [and rinsing denotes immersion in a miqveh — Translator]; and we accept their words. Nevertheless, the literal meaning of the verse remains: Whenever a man suffering from a flow touches someone who is ritually pure — if his hands had been rinsed, then the person touched becomes ritually impure, but not his clothes; if his hands were unwashed, they also render one’s clothes ritually impure.

AND WHOMSOEVER ‘HAZAV’ (HE THAT HATH THE ISSUE) TOUCHETH, WITHOUT HAVING RINSED HIS HANDS IN WATER, HE SHALL WASH HIS CLOTHES, AND BATHE HIMSELF IN WATER, AND BE UNCLEAN UNTIL THE EVEN. Scripture calls the immersion [of the whole body of the impure object] “rinsing in water,” become pure, he must immerse himself completely in water, this being implied in the term shataph (rinsing), as the following verse indicates. And the reason why Scripture uses the term “rinsing,” and why also it speaks here only of the hands having been rinsed, will be explained further on in the text. as is indicated by the verse here stating, and every vessel of wood [touched by a zav] shall be ‘rinsed’ in water [which means completely “immersed” in water], and similarly it calls the immersion of an [impure] garment “washing,” thus saying, then it shall be ‘washed’ the second time, and shall be clean. The reason for these expressions is that it is necessary that there should be nothing interposing during the immersion [between the water and the utensil or the person], but he is to rinse his whole body in the water, even as the verse states, it shall be scoured, and rinsed in water, similar to the expression, ‘nachal shoteiph’ (an overflowing stream). And the meaning of the verse [here which specifies the hands] is because touching is done with the hands; therefore the verse states that when the zav touches anyone with his hands, and he has not “rinsed” them yet [i.e., “immersed” them, as explained above] by “rinsing” his whole body in water, that other person is impure. This is as if the verse had said, “and whomsoever he that hath the issue toucheth with his hands, and he hath not yet bathed himself in water on the day of his purification, he shall wash his clothes, [and be impure until the even].” Scripture had to use the term “rinsing,” in order to teach that the “bathing” it mentioned in the verse, and he shall bathe his flesh in running water, should be by means of rinsing and rubbing, so as to remove anything interposing [between the water and his body], as I have explained. It would not have been correct for Scripture to say that “whomsoever he that has an issue touches, after having rinsed his hands in water, will not be rendered impure,” [from which we would deduce that if he has not rinsed his hands in water, he shall be impure, thus indicating that his impurity is conveyed through his …

. וידיו לא שטף במים, the zav did not immerse himself in a ritual bath.. This is the way the sages interpret the words above (compare Rashi) Personally, I believe that the plain meaning of these words above is that the person experiencing these drippings and sticky semen adhering to his flesh mentioned in verse 3 has not yet removed this from himself. The Torah uses an elegant way saying “he has not washed it off with water,” basically, it refers to a removal by wiping or scraping his skin including his glans. The lesson here is that a simple immersion in a ritual bath, if not after the removal of the offending material, does not accomplish its purpose of ritually cleansing the afflicted party. This has been explained in detail in Niddah 15 where the words in our verse are understood as “although he had previously immersed himself he still remains ritually impure, seeing he had not first cleansed himself physically. Spiritual cleanliness presupposes physical cleanliness.” Anything or anyone touching the offending fluid (until it has thoroughly dried, congealed) becomes contaminated ritually.
The expression שטיפת ידיו במים, loosely translated as “immersing one’s hands in water,” is used here in a sense similar to Proverbs 30,20 where the author describes the unfaithful wife as “wiping her mouth” after indulging in illicit sex, proclaiming that now that she has “wiped the offending residue of her indulgence,” she has not committed any sin. Solomon describes the scenario sarcastically, of course. A similar scenario occurs in Judges 3,24, where Eglon’s servants assumed that their king was still busy using his private toilet and this was why he did not open the door for them. The expression used there was מסיך הוא את רגליו, an elegant way of referring to someone urinating or excreting.
Here the Torah uses the elegant way of referring to the sticky mess still adhering to the afflicted party’s body as ידיו לא שטף במים, “he did not rinse his hands in water.” In other words, he had not yet gotten rid of the offensive material causing the ritual impurity in the first place. The expression is used without recourse to elegance in Leviticus 6,21 where the words ומורק ושוטף במים mean: ”it has to be purged and thoroughly rinsed out in water.” The fatty substances of the sin offering in that vessel have to be cleaned out. In Isaiah 28,2 we also read about מים כבירים שוטפים, “the destructive force of mighty waters.” It sweeps away anything before its force, “cleans” it out. In Job 14,19 we also encounter the expression שטף in that sense, i.e. “torrents wash away earth.”