Flushing a Toilet on Shabbat
It goes without saying that flushing a toilet is permitted on Shabbat. There is some discussion, however, whether it is permissible to flush a toilet that is equipped with a disinfectant device that colors the water as it is flushed. It is virtually unanimous among halachic authorities that one should not flush such a toilet on Shabbat. This is because doing so might be a violation of tzoveiah, the prohibition against coloring a substance or item on Shabbat. As such, those who use such devices in their home should remove them before Shabbat.
One who is faced with no choice but to use a toilet whose water will be colored by flushing it has a few options to choose from. There are grounds to be lenient with the disinfecting devices that are affixed to the top of the tank rather than the bowl of the toilet. This is because when the toilet is flushed, the water is not colored right away. The coloring only occurs after the water in the tank is refilled and reaches the top. The delay between the flushing of the toilet and the coloring of the water, a concept known as gramma, is what forms the basis for leniency in extenuating circumstances.
Disinfectant devices that are affixed to the rim of the toilet bowl are more problematic as the coloring takes place as soon as the toilet is flushed. In such a situation, one should remove the disinfectant device before flushing the toilet, preferably in an indirect manner. If even this is not possible, then the toilet may be flushed due to the principle of kavod habriot. In this case, however, it is preferable for one to flush the toilet with a shinui, in an irregular manner, such as with one’s elbow, or the back of one’s hand.
A toilet that became clogged may be pumped with a common household plunger. However, it is preferable to pump the toilet with a shinui, such as with one’s weaker hand, and the like. Even more preferable would be to ask a non-Jew to pump the toilet, should there be one available. Nevertheless, if neither of these options is possible then one is permitted to pump the toilet in the regular manner. Once again, it is largely due to the principle of kavod habriot that one is permitted to unclog a toilet on Shabbat. There is an opinion that a toilet that has become completely blocked and unusable may only be pumped by a non-Jew.
 Shulchan Shlomo 320:31-3.
 Tzitz Eliezer 14:47; Be'er Moshe 2:28; Az Nidberu 12:13.
 Minchat Yitzchak 5:75. Note: This ruling is based largely on OC 336:9.
 Igrot Moshe 4:40.