Flushing a Toilet with a Coloring Disinfectant on Shabbos
My toilet has an automatic bowl cleaner that colors the water. May I flush it on Shabbos?
Automatic toilet bowl cleaners and disinfectants dispense some liquid into the toilet bowl each time the toilet is flushed; if the product is colored, it will color the water in the bowl. Contemporary poskim are divided on whether flushing the toilet on Shabbos—if the product is colored—is a violation of the melachah (forbidden act) of tzoveiah (dyeing).
Some argue that it’s no problem since coloring the water is considered a grama (an indirect result of flushing the toilet), and because the primary intention isn’t to color the water, but to clean the toilet. They also base their position on the halachah that tzoveiah doesn’t apply to water, especially if the water in question isn’t used to color something else.
Other poskim counter that the coloring of the water should be regarded as intentional and as a direct act, and not a grama. In addition, according to their opinion, liquid that’s not intended for drinking isn’t exempt from tzoveiah. Therefore, flushing the water in this manner is forbidden, and in their opinion – it might even be an issur d’Oraisa (biblical prohibition).
In practice, the halachah depends on whether one’s intention is to color the water or just to clean the toilet. If one’s intention is simply to clean the toilet, it’s permissible; however, if one also appreciates the fact that the water looks nice and clean due to its color it’s forbidden.
Many poskim say that the melachah of molid reiach (the prohibition of creating a scent on Shabbos) is not a problem in this case. One of the many reasons they give is that one’s intention isn’t to create a new smell, but rather to eliminate a bad one.
https://halacha2go.com?number=567