Q. Is there a problem to use an under the sink filter cartridge on shabbos? I noticed in some shuls the tap for filtered water is covered on Shabbos.
A. Poskim maintain that the most plausible melocho involved in using a water filter is Merakaid (sifting or straining) since unlike the melocho of Borer or Zoreh, it always involves using an utensil (Igley Tal – Zoreh 3: 1, see also Rambam – H. Shabbos 8: 11, on wine filtering or meshamer, that seems to hesitate which is the applicable melocho, Merakaid or Borer). The downside of Merakaid is that there is no hetter for separating the wanted (oichel) from the non-wanted (pessoles) or for doing it immediately before eating (somuch leseudoh) as in Borer. However some maintain it is Borer (see Chazon Ish – Shabbos 53
Poskim, (Mishna Berura 319; 40 quoting Ran). also differentiate between three classes of liquids, depending on unsuitability of the unfiltered fluid. They range from total (akurim – Biblically prohibited), partial (akurim k'zas, rabbinical prohibition) or clear (tzlulim- permitted).
In developed countries, where most people drink the unfiltered tap water, added aerators and filters do little to improve the quality of water already treated and are therefore permitted.(Chazon Ish O.H. 53).
However, in places where the filters are needed to remove health-safe living organisms that can be seen with the naked eye, Minchas Yitzchok (7: 23) and other Poiskim permit using a filter (see Chayei Odom 16: 8 and Ohr Yisroel p. 75) since most people would still drink the unfiltered water as it is only prohibited by dint of Torah law. They recommend not using the first water that comes out from the tap.
Horav Shlomo Miller Shlit"a agrees with the above, especially since it became the normal way of using that water.
There is a further issue of concern, and it is the fact that while the water is inside the filter it could be regarded as akurim, since at that point most would not consume it, However Chazon Ish (ibid.) permits (Palgei Maim p.136). Horav Shlomo Miller's Shlit"a opinion is that it is regarded derech hilucho or the normal process done when using the tap. He also recommends discarding the first water that comes out.
Rabbi A. Bartfeld as revise by Horav Shlomo Miller Shlit"a
Important Numbers
