Then according to your line of thinking, don’t open your water faucet, because you are bringing in water from a Reshus hoRabim to a Reshus haYochid, and when water & crumbs goes down your sink drain, it will go back to a Reshus hoRabim.
Fortunately, I have learned tractate Shabbos, and IY’H look forward to recommencing tractate Shabbos on Chamishi shel Sukkos courtesy of Ushpizin Moshe when 13th cycle commences tractate Shabbos, and when you shall be learning tractate Shabbos on the 13th cycle, you shall soon become acquainted with the fact, that below a certain level under the ground, where your water pipes run, there is no such thing as a Reshus hoRabbim.