May one load a dishwasher on Shabbos?

We previously learned that one may not operate a dishwasher on Shabbos even when set to operate with a time switch.

The issue at hand involves hachana – preparing for after Shabbos. Chazal prohibited preparing on Shabbos for after Shabbos and this halacha manifests itself in many ways. For example, one may not bring wine on Shabbos from a storeroom for havdalah, [1] because one is performing an action for after Shabbos even though it does not involve a melacha. One may not prepare clothes on Shabbos to wear after Shabbos. [2]

Preface: It is extremely complicated to define hachana and therefore we will only present basic concepts.

…and dishes in a dishwasher?

It depends on one’s routine. If during the week one places dirty dishes straight from the table into the dishwasher, one may do so on Shabbos as well. [3] This is not considered hachana because it is similar to placing dishes in the sink after eating.

We are referring to a dishwasher that is also used to store dishes after washing. If the dishwasher is only used for washing and the dishes are subsequently removed, a rav must be asked. [4]

But is that not preparing dishes for washing?

It is in a way but not entirely. Just like one does not view placing dishes in the sink as hachana, rather as merely clearing the table and putting dirty dishes in order, so too placing dishes in the dishwasher is clearing the table and not hachana. We do not attempt to fool ourselves in thinking that dishes in the dishwasher or sink are not intended for washing. However, since the action is not a direct hachana, because it is viewed as ‘clearing the table’, it is permitted.

What if I first put them in the sink?

If during the meal the dirty dishes are placed in the sink it is prohibited to then subsequently transfer them to the dishwasher. This is a perfect act of hachana. [5] However, if the sight of dirty dishes bothers members of the household, one may place them in the dishwasher. [6] One needs to be honest and think of why one places them in the dishwasher.

And yet, there still remains a problem. Many dishwashers will not clean the dishes properly unless rinsed before being placed in the dishwasher. Rinsing them in the sink and placing them in the dishwasher is hachana, because if one merely wished to put them out of site, one would place them in the dishwasher without rinsing them. See below.

To summarize:

• If one routinely places dishes from the table into the dishwasher, one may do so on Shabbos as well.
• Once placed in the sink they may not be transferred to the dishwasher unless the sight of dirty dishes bothers members of the household.
• The dishes may not be rinsed before being placed in the dishwasher. See below.

Are there problems of borer when loading a dishwasher?

Silverware and dishes that are in a mixture may not be sorted out in order to place them in the dishwasher. [7] One may remove the large dishes from the table that are not in a mixture and place them in dishwasher and then remove the small dishes. The same can be said of the silverware.

Is it permitted to wash dishes on Shabbos?

One may wash dishes on Shabbos when those dishes are to be used again that Shabbos. [8] Accordingly therefore, one may wash dishes on Friday night when the same dishes are to be used on Shabbos day. If one is eating out on Shabbos day, the Friday night dishes may not be washed because it is hachana for after Shabbos.

What about soaking pots and dishes on Shabbos?

This too relates to hachana because it is one thing to place dishes, pots and silverware in the sink after use, but soaking or lightly rinsing them seems to be hachana.

And yet, there is a solution.

If for example, flies are attracted to dirty pots and pans, one may rinse or soak them in water. [9]

It is accepted practice to soak or rinse dishes in water in order to prevent food residue from sticking, which will make cleaning harder. Although this appears as hachana, the poskim tend to define such an action as ‘prevention’. [10]

An action performed on Shabbos that is intended to prevent a loss; or intended to prevent extra work is not hachana prohibited by Chazal. Soaking dishes on Shabbos to prevent food sticking to the dishes is to prevent extra work after Shabbos and therefore permitted.

If however the food has already stuck to the plates, it is ossur to soak or rinse them in water, because it is something one will have to do after Shabbos in any case and is hachana. [11]

As per the dishwasher above, one would be permitted to lightly rinse the dishes before inserting them in the dishwasher to prevent residue sticking to the dishes.