When my daughter was in nursery school, I had the opportunity to visit the class and observe daily activities. The children came in from the playground, lined up, and were instructed to “wash” their hands by plunging them into a basin of water. One after another, the 20 pairs of hands were submerged in the same basin. I cringed when I thought of all the shared dirt and germs in that water and how that approach to washing was not hygienic. It also did not conform to the practices of Jewish ritual hand washing.

Jewish ritual hand washing is never done by immersing the hands in a basin of standing water. It involves pouring clean water from a cup over the hands, alternating from one hand to the other. Is Jewish ritual hand washing effective in reducing infection and improving health?

Ritual hand washing, or netilat yadayim, has biblical origins. In Exodus 30:17-21, God commanded Moses to make a copper laver for the kohanim (priests), Aaron and his sons. “When they go into the tabernacle of the congregation, they shall wash with water, that they die not…. [S]o shall they wash their hands and their feet, that they die not; and it shall be a statute forever to them, even to him and to his seed throughout their generations.” The biblical text is glaringly clear – wash your hands, or you will die.

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In Leviticus 15:1-13, God commands Moses and Aaron how to deal with a man who has a zav, or “running issue out of his flesh.” This passage appears to refer to a contagious disease, which has been interpreted by some to be gonorrhea. God directs Moses and Aaron how to decontaminate those who have been exposed to the zav. The purification includes washing clothes, bathing in water, rinsing hands in water, washing wooden vessels, and destroying clay vessels touched by the patient.

Hand washing also is described in Deuteronomy 21:6-7 as part of a ritual carried out by elders of the nearest city if a murder victim is discovered in a field. “And all the elders of that city … shall wash their hands … and say, ‘Our hands have not shed this blood.'” In this case, hand washing is a symbolic ritual, declaring the innocence of the town’s leaders, who failed to find the perpetrator.

Over 300 references

After the destruction of the Second Temple in 70 C.E., rabbinic leaders transferred some Temple practices to everyday life. For instance, Temple sacrifices were replaced by synagogue prayer services. In addition, the dinner table in the home was considered analogous to the Temple altar; hence, the sages commanded that Jews wash their hands before breaking bread, as the priests washed before offering sacrifices. Since hand washing was part of Temple worship, it became of tremendous importance in many post-Temple rituals. The Talmud has more than 300 references to hand washing, including descriptions of how to do it, the source of water to use, and when it is needed.

In the Babylonian Talmud tractate B’rachot, the notion of washing after defecation was introduced. “Rabbi Yochanan also said: ‘If one desires to accept upon himself the yoke of the kingdom of heaven in the most complete manner, he should turn aside, then wash his hands, then put on t’fillin, then recite the Sh’ma and say the morning prayers.'” (See BT B’rachot 14b.) “Turn aside,” is a euphemism for defecation, and the best religious practices demanded hand washing after defecation. The practice of washing the hands took on such significance that it was reported that the great sage Rabbi Akiva, when confined to a Roman prison, declared that he would rather die than eat without first washing his hands. (See BT Eiruvin 21b.)

Ritual hand washing has retained significance in modern Jewish observance. Anyone who has attended a Passover seder knows that we wash our hands ritually twice during the evening: First, without a blessing, before dipping and eating the karpas (greenery), and later, with a blessing, before eating the matzah and the meal.

Observant Jews wash before eating any bread or matzah, and make the blessing, “Blessed are You, Lord our God, King of the universe, who has sanctified us with His commandments, and commanded us to wash hands.” A special cup with two handles typically is used. The cup is filled with water and the water is poured twice over each hand. In the spirit of enhancing Jewish practice, it is now possible to purchase beautifully crafted and artistically decorated washing cups, many of which are made in Israel.

Finger-rinsing good                       

Some Jews also practice hand washing after the meal. The so-called “last waters,” or “mayim acharonim,” is believed to have originated for other health reasons. Before refrigeration was invented, large amounts of salt were used to preserve food. If the fingers had salt residue after eating, touching the eyes could cause eye irritation or even blindness, so rinsing the fingers after eating was implemented.

Hand washing also is practiced as part of the morning ritual. When they wake up in the morning, observant Jews will rinse their hands with negel vasser – literally “nail water”. Judaism teaches that during the night the soul leaves the body; God returns it every morning. Hand washing is the first act performed in the morning, to purify the person in case he has touched private areas of the body, and to sanctify and prepare the person for service to God.

Many Jews practice ritual hand washing after touching objects that could convey impurity, such as leather shoes or ritually unclean animals, or after visiting a cemetery. Ritual hand washing also may be performed after using the bathroom, cutting one’s nails or hair, touching the genitalia, or after having a seminal emission. In addition, before the kohanim bless the congregation in synagogue, they remove their shoes, and then have their hands ritually washed by Levites, people in the congregation who are descendants of the tribe of Levi.

Modern medical research has clearly demonstrated the benefits of washing hands after using the bathroom and before eating. Many studies have shown that washing hands with soap and water reduces the incidence of infectious diseases and improves health. For instance, scientists at University of Michigan School of Public Health conducted an analysis of 30 studies on hand hygiene. The data showed that improvements in hand hygiene reduced the incidence of gastrointestinal illness by 31 percent and respiratory illness by 21 percent.

Of course, the relevant question is whether hand washing with plain water, as is done in ritual hand washing, reduces infections, thereby improving health. There still are places on the globe where soap is a luxury, so this question is of more than academic interest, and has serious health related implications for many people.

The surveys say…

Researchers at the International Centre for Diarrhoeal Disease Research in Bangladesh studied hand washing after defecation. The data show that “less than 1 percent used soap and water for hand washing before eating and/or feeding a child. More commonly, people washed their hands only with water, 23 percent after defecation and 5 percent before eating.”

The scientists at that institute compared “children living in households where persons prepared food without washing their hands, [to] children living in households where the food preparer washed at least one hand with water only, washed both hands with water only, or washed at least one hand with soap.” The study concluded that washing “with water alone can significantly reduce childhood diarrhea.”

Researchers at the London School of Hygiene and Tropical Medicine confirmed the value of hand washing with soap, as well as with water alone. They studied 20 volunteers who contaminated their hands by touching handrails and doorknobs at the British Museum, the London bus, and the underground (subway). Subjects were directed to travel on the bus or underground and tour the museum, wiping their hands over public surfaces. They were then directed to wash their hands with soap and water, wash with water alone, or not to wash at all. Each volunteer completed the contamination/cleansing sequence 24 times: 8 times cleansing with soap and water, 8 times with water alone, and 8 times without washing. Their hands then were tested for bacteria.

When hands were not washed after contamination, bacteria of fecal origin were found in 44 percent of samples. When plain soap and water were used to wash hands, fecal bacteria were found in only 8 percent of samples. This shows that our modern conventional approach to hygiene, washing with soap and water, is highly effective (although not perfect).

When water alone was used, fecal bacteria were found in 23 percent of samples. So water alone, although not as effective as soap and water, can reduce contamination significantly, from 44 percent to 23 percent of samples. This suggests that ritual hand washing, which uses water alone, can be effective in reducing bacteria on hands. In ancient societies, when hygienic practices were not routine, the simple act of rinsing hands with water most likely reduced rates of infection and helped to keep the community healthy.

Likewise today, when observant Jews ritually wash their hands before eating bread, and at other times, the act of ritual washing with plain water can reduce bacteria and have positive effects on health. Ritual hand washing also raises awareness of hand hygiene in general, and may influence people to wash more scrupulously with soap and water as well. Thus, the biblical injunction to “wash with water that they die not,” and rabbinic interpretations of the ancient traditions on hand washing, contribute to the spiritual, as well as the physical, health of individuals and the community.

Miryam Z. Wahrman, Ph.D., is professor of biology at William Paterson University, where she studies bacterial contamination of fabrics and other environmental surfaces. Not only is she the science correspondent for The Jewish Standard, she also is an avid hand washer.