Tosfos says that even if mei geshamim would not come to mei kilon, but if the water would run out, there would be a separate issur, based on the concern that a person might be tore'ach to bring water from a far off place, like we see later on in the Gemara. My questions are:
a) if you're dealing with a case where the water runs out, you WILL encounter the chisaron of coming to mei kilon. How is it possible to have a case of mei geshamim that does NOT come to mei kilon, but still runs out?
b)where in the Gemara is Tosfos' source for this chashash that you might be tore'ach to bring water from a far off place?
c)When the Gemara asks frm Mishnah that naharos ha'moshchin should be assur because they're mei geshamim, which the Mishnah assurs, the Gemara answers "the naharos don't run out". That's mashma that mei geshamim of Mishnah DO run out. But Tosfos told us the Mishnah is NOT dealing with mei geshmamim that run out?
Thanks in advance!
(p.s. it seems that the Chazon Ish deals with my questions on Tosfos in Hilchos Chol HaMoed Siman 134, but I cannot understand what he's getting at)
dan s., palo alto, ca
(a) It is possible if the pool of water is shallow. I see that you have understood Tosfos to be saying that there is a prohibition due to a Chashash of Paski even when there is no possibility of Mei Kilon.
(b) The source is from the Gemara about Pesikos and Bereichos, and from the Gemara about Bereichah she'Notefes. See Rashi DH Tishti and DH Amar Abaye.
(c) Tosfos says that we are talking about Mei Geshamim that we know from our estimations will not run out. However they are not of such a magnitude that they are of a type that similar pools of Mei Geshamim in different circumstances could not run out. The Gemara means that water in Bavel is so plentiful that the rivers are of a type that never dry up.
(d) The main points of the Chazon Ish (I presume you refer to OC 134:10) are as follows:
(1) See Chazon Ish (ibid. 9) who explains why springs are permitted in the Mishnah as opposed to Mei Geshamim. He also explained there that this Heter applies even where the spring may potentially dry up. Nevertheless, the Mishnah prohibits Mei Geshamim where there is the possibility that they would dry up. Also Mei Geshamim is prohibited even where the water is shallow and there is no problem of Mei Kilon (see (a) above).
(2) If the water is of the type that could theoretically dry up, even in different circumstances they are considered "Paski". (See Chazon Ish ibid. 8.)
(3) Even if the water will diminish only to an extent that they are Mei Kilon they would be considered Paski.
Dov Freedman