Dishwasher on Shabbat

Dishwashers are so useful that people begin to wonder, "Why didn't they think of this before?" And in fact dishwashers are becoming more and more commonplace, so much so that some households are centered around the dishwasher. However, on Shabbat, when the entire family is together, huge piles of dirty dishes are collected! Does this mean that Shabbat is the time to roll up our sleeves and go to work? Can't the timers which solved our problems with lighting, heating, and cooling also be harnessed to this task?

 The Zomet Institute is convinced that using a dishwasher on Shabbat is not only permitted under the conditions to be explained below but that it is a valuable and proper goal. We have been taught by the late Rabbi S.Z. Auerbach that the "enjoyment of Shabbat" is an obligation decreed by the prophets ("You shall cry out your joy of Shabbat" [Yeshayahu 58:13]), and that this obligation takes precedence over "fears of stringencies." There are several essential conditions for using a dishwasher on Shabbat, and if these are ignored the equipment cannot be used. It is highly recommended that before buying a dishwasher one should carefully read the instructions for choosing a dishwasher suitable for Shabbat. Some dishwashers are such that they are very limited in the way they can be used!

The conditions for using a dishwasher on Shabbat are as follows:

 (1) The soap (bar, powder, or liquid) must be placed in the main cavity of the washer (and not in a slot in the door) before Shabbat.

 (2) The inlet water valve must be turned on before Shabbat. It is strictly forbidden to open the valve on Shabbat.

Explanation: Perhaps the soap was not cooked during its manufacture, and "cooking" it on Shabbat is forbidden. If it is placed in the washer's main cavity, it will cook without human intervention. However, if it is put in the door, the act of closing the door causes the soap to be "cooked," and an act that even indirectly leads to "cooking" is prohibited. In addition, opening the inlet valve on Shabbat allows cold water to enter the machine, and this water is "cooked" when it is heated.

 Since new soap cannot be added to the washer, only one wash cycle (with soap) will be permitted per Shabbat.

 (3) The switch that turns the dishwasher off when the door is opened must be disconnected.

Explanation:  Dishwashers usually have a safety switch that turns the washer off if the door is opened. Thus, closing the door on Shabbat (after the dishes have been placed inside) is what allows the timer to turn the machine on, and it is therefore forbidden to operate this switch on Shabbat. A technician can be called to permanently disconnect the switch or to connect it to a Shabbat/weekday selector. The correct way to disconnect the safety switch depends on the details of the dishwasher, and it is therefore recommended to consult the instructions for choosing a dishwasher suitable for Shabbat before buying a new dishwasher.

 (4) The timer should be set so that the dishwasher will run late at night.

Explanation: We are not concerned about making noise, just as we allow operating an air conditioner and many other types of equipment through use of a timer (the Shulchan Aruch gives an example of a clock that chimes every hour). However, to emphasize the fact that the machine is operated by a timer and not manually, it is best that the washer be turned on when all the residents are asleep. This also provides added safety, especially for children, since as noted above the safety switch in the door will be disconnected on Shabbat.

 (5) The dishwasher can only be used for one washing cycle during Shabbat.

Digitally operated dishwashers usually have in internal timer that allows only one washing cycle to be scheduled. An external timer cannot be used for such equipment to operate additional cycles, since it will not start unless the "start" button is manually pressed. Mechanically operated washers also require the timer to be readjusted in order to start a new batch. For these reasons, the washer can be operated only one time during Shabbat.

The only way to operate a digital washer which does not have an internal timer is to set it for full operation before Shabbat and then to turn off the current source by using a timer. For more details, see the instructions for choosing a dishwasher suitable for Shabbat.

 (6) On holidays, some rabbis are lenient with respect to the possibility of indirectly "causing a flame to be lit," and according to this approach an external timer can be used on a holiday to operate a mechanically controlled dishwasher more than once. This can be done if the internal timer button is moved to the beginning of a new cycle after the current has been turned off by the timer. This is of course impossible in an electronic dishwasher, where the only way to begin the operation is by pressing the start button.

  We note in passing that The Zomet Institute does not approve of using the same dishwasher for both meat and dairy dishes. This would involve a complex cleaning process, including removing what remains stuck to the grills, replacing the dish rack, and ritual purification of the dishwasher.

More details are available from the following sources (in Hebrew):

• Rabbi Gideon Pearl, Using a dishwasher – Kashrut and Shabbat, Techumin 11
• Rabbi Shlomo Levi, Using a dishwasher on Shabbat and a holiday, Techumin 11
• Rabbi Yechiel Paust, Operating a home dishwasher with a Shabbat timer, Techumin 11