A Clinician’s Guide to Showering on Shabbos
Clinicians can be exposed to many infectious diseases during a hospital shift. Cleanliness and hygiene are of the utmost importance to prevent the spread of disease. Therefore, there are guidelines in place, like donning PPE, to ensure illness isn't spread. Another suggestion is showering after a shift; the use of hot water is another way to ensure complete disinfection. This raises the following dilemma. Can one shower on Shabbos to reduce the risk of an illness spreading?
There are many factors here. First, can one shower if it is not a real risk to oneself? What about potentially spreading disease amongst others? Obviously, when it is a situation of hatzalos nafashos, saving lives, then one is justified in desecrating Shabbos. However, there are many halachic factors behind showering.
The majority of the forbidden activities on Shabbos stem from the 39 Malachos. These malachos were carried out in preparation for and performed in the Mishkan. Part of the Mishkan's activities was boiling herbs for sacrifices and dyes for the bigdei kehunah. Therefore the act of bishul, boiling, is forbidden on Shabbos. However, the Gemara in Shabbos (41a) says that boiling is forbidden if boiled to a certain temperature; however, if not, it is permissible. This temperature is around 47 degrees Celsius, which is learned from the halachos of Shechitah. In general, this is referred to as Yad Soledis Bo. Although one may bathe (rechitzah) at a permissible temperature, the rabbis enacted a stringency that one could not because it may lead to lighting a fire to heat water and, therefore, transgress the melacha of Havara. (Shulchan Aruch 326:1) However, contemporary Poskim dispute whether bathing in hot water cooler than Yad Soledes Bo is permitted. Rav Asher Weiss (in his new Kuntres about the Coronavirus outbreak, Teshuvos Ketzaros p. 47) ruled that medical personnel may be lenient in this matter as it is a Sha’as ha’Dechak and perhaps even a matter of Pikuach Nefesh.
Although this implies that one may take a shower, one should be aware of the water systems in place where they are taking a shower because each system can potentially have a problem.
In Israel, it is common for hospitals to have a thermostat regulating the temperature (around 45 degrees) to be halachically permitted, and therefore, a clinician would be able to take a shower. However, in America, it is unknown and impossible to regulate the shower temperature; hence, taking a shower in an American hospital is forbidden. The same would apply to a tankless water heater and gas boiler. This works by inducing either a flame or electricity to ignite as soon as one turns on the faucet. Therefore, it would be forbidden to use this type of method on Shabbos. However one may ask a non-jew to turn on and off the faucets, and one may not adjust them. As this may seem unreasonable, one can also rely on a shinui, and perform the action in an abnormal fashion.
An example of a permissible hot water system is the electric boiler. The way the boiler works is that when hot water is used it is activated to heat up the cold water. Therefore, if one has this system, one should turn off the boiler before shabbos. There is also no need to worry about the hot water heating up the new cold water because it can be assumed that the hot water isn't considered Yad Soleidies Bo. Suppose there is a thermostat where the water can be regulated to a specific temp. One can set it to 45 degrees and less so no bishul can occur. One does not need to worry about Havara, the new cold water that will be heated, because it is considered a grama and is indirect. Additionally, it is Davar She’eino Mischavein, meaning it is a matter that you did not intend to occur.
Regardless, when taking a shower, a person should ensure that he doesn’t inadvertently violate other Halachos of Shabbos, such as squeezing water out of his hair or out of a towel. He should also use liquid soap and not bar soap.
Adapted from medicalhalacha.org