Rabbi Mendel Agranovich
Hello, dear readers! In this issue, we will devote our article to a practical topic: using hot water on Shabbat.
Part 1. Electric Water Heater
In Israel, these appliances are generally used on cloudy days, when there is not enough solar energy to heat the required amount of water.
Technically, the appliance is extremely simple: the water heater consists of a heating element and a huge tank. It is switched on from inside the apartment, but it also has a separate shutoff button beside the tank.
Two points are worth noting:
1) The water heater has a safety cutoff that stops it from heating if the pressure in the system reaches a critical level. There is therefore no need to worry if you forgot to switch it off before Shabbat. If your water heater has such a safety cutoff and it is working properly, this poses no risk other than high electricity costs.
2) When we use water from the heater, cold water from the water supply automatically replaces the water that has flowed out, following the principle of communicating vessels. Therefore, even if the heater is disconnected from the power supply, one may not turn on the hot water, because the incoming water will heat up in a primary vessel that has been removed from the heat, which is essentially what this appliance is.
A reasonable question arises: since water enters the heater according to the laws of physics, as an indirect result of the user's actions, why is this forbidden? After all, we know that the Torah prohibited only a direct action, as can be seen from the Shulchan Aruch and the Rema in section 334, paragraph 22.
The answer is as follows: since the entire system is designed to work this way, we cannot claim that this action is indirect. We rely on it from the outset in our everyday use, and this is how the mechanism for refilling the tank works. In the situation described in the Shulchan Aruch and the Rema, however, when the fire reaches new clay vessels filled with water, its heat causes them to burst and extinguish the fire without any human involvement. The person's action is limited to placing these still-unfired pots in the path of the fire, knowing that they will not withstand the heat and will burst. Even if he deliberately fills them with water and places them in the fire's path, he still takes no part in the extinguishing process.
The authors of Orchot Shabbat (chapter 1, note 197) cite another important point—one might even call it decisive—in the name of Rav Shlomo Zalman Auerbach: as soon as we open the tap, water immediately enters the hot-water tank, and this is therefore considered our direct action.
Practical conclusion:
1. One may not use hot water from an electric water heater on Shabbat.
2. If the temperature of the water in the heater is below the minimum threshold of 45 degrees Celsius (this should be checked before Shabbat, making sure that the water has cooled inside the heater itself, and not just in the tap and pipes), the weather is cloudy, and, of course, the heater is disconnected from the power supply, one may use the hot water to wash hands, face, or feet, or attend to an adult's or child's personal hygiene (Orchot Shabbat, notes 198 and 201, and Mishnah Berurah, 326, paragraph 1).
3. One may not take a full-body shower or bath in hot water on Shabbat (ibid.).
How, then, can one wash a child on Shabbat, given that most halachic authorities prohibit using wet wipes on Shabbat? As we have written before, and will repeat here, one may leave a kettle of hot water that came to a boil before Shabbat, with the kettle now in “Shabbat” mode (this refers to a special “Shabbat” kettle). Pour water from it into a dry basin and add cold water until it reaches the temperature you need. Another option requires more care, but is also permitted from the outset: fill a basin with plenty of cold water and add an amount of hot water from the kettle that will leave the resulting mixture clearly below 45 degrees Celsius (Mishnah Berurah, 318:84).
If you accidentally turn on the hot-water tap on Shabbat, is it better to close it or leave the water running until Shabbat ends? Let us explain the question: if we close it, the water that has entered the system will be heated by the hot water in the heater; but if we leave it open, more and more water will drain out, and correspondingly more water will enter the heater. The authors of Orchot Shabbat give the following answer: if the water in the heater is very hot, it is better to close the tap, because it will take a long time for the entire tank to drain and cool, and fresh quantities of water will keep entering and heating up. It is therefore better to minimize the amount entering. But if the water in the heater is only slightly above 45 degrees Celsius, it is better to let it drain as quickly as possible, thereby preventing even the first quantity of water that entered on Shabbat from being cooked in the water already in the heater.
The tap may be closed once the water inside the heater itself falls below 45 degrees Celsius, and certainly once it becomes completely cold. However, there is no need to wait until it becomes cold if we are certain that the water in the heater has cooled below 45 degrees.
Part 2. Gas and Electric Heaters
A system in which opening the hot-water tap activates a gas or electric heater may not be used on Shabbat.
If the tap was opened accidentally, one may not close it, because doing so will shut off the gas or electric heater. However, if family members are worried and do not want to leave the gas burning throughout Shabbat, one may hint to a non-Jew to turn off the water. For example, one may say, “Anyone who puts it out will not lose out by doing so,” or, “The gas is burning, and I cannot close the tap or put it out.” The non-Jew then makes the decision independently, and you do not violate the rabbinic prohibition against asking a non-Jew to perform a forbidden action on Shabbat. According to Rav Shlomo Zalman Auerbach, one may also ask a non-Jew to close the tap and turn off the switch in an unusual way, such as with an elbow, and this request may be made directly, without hints. This method is possible, but its permissibility is not clear-cut. Therefore, although the previous option is more difficult to carry out, it is preferable from a halachic standpoint.
To be continued...
Shabbat Shalom!