Coloring water on Shabbat

Hi,

May I keep a cleaning tablet in the tank of a toilet, if it will dye water which is introduced on Shabbos?

The act of colouring is prohibited on Shabbos, but many authorities rule that this does not apply to colouring food. Therefore, halachic authorities tend to permit adding juice to water or red wine to white wine, where the intent is not to change the colour. However, halachic authorities differ on the application to toilet water.

Those who permit this do so because: 1) The water is potable, and so is food; 2) One intends to clean, not to dye; 3) The water is not meant to remain long-term; 4) One colours the water only indirectly, when flushing. Those who prohibit argue that the water is not meant for drinking, and that people do want the colour. Rabbi Korobkin states that our practice is to prohibit.

(Beis Yosef Orach Chaim 320 katav; Shulchan Aruch Orach Chaim 320:19-20; Chasam Sofer Shabbos 74b; Mishneh Berurah 318:39, 320:56, 59; Tzitz Eliezer 14:47; Shemiras Shabbos k'Hilchasah 3:21, 23:14 and footnotes)

Have a great Yom Tov,
Mordechai