In NYC certain poskim say that the drinking water needs to be filtered in order to take out bugs. The reality of my apartment is that my kitchen sink can’t be filtered properly because the special filter that is reasonably priced to take out tiny bugs won’t fit on the faucet. In order to install other filters I would have to get permission from my landlord and pay for the filters to be installed. This would cost a lot more money. My other option is to put the reasonalbly priced special bug filter on the bathroom faucet where filter fits right on the faucet and then get water in pressing situations from the bathroom sink. Is there anything wrong with getting water from the bathrooom sink to be used for cooking in needed situations?
It is permitted to use water from the bathroom sink.
Sources: Even food that has been touched before netilas yadayim in the morning, is permitted to eat post facto (Mishnah Berurah, 4:14), and although other poskim are stringent (see Kaf Hachaim 4:20), the same would apply to foods brought into a bathroom. This halachah applies to a “real bathroom,” meaning a beis hakisei of Chazal. Poskim debate whether our bathrooms are considered a beis hakisei or not, and this provides further room for leniency. Moreover, in a bathroom that includes a sink as well as a toilet, and which is used for purposes other than excusing oneself, the issue of ruach ra’ah may not apply at all, and one can use the water from the sink even on a regular basis. A similar ruling is given by Teshuvos Vehanhagos 2:4.