Q. In crisis times when we can’t go to the mikva and we pour nine kavim of water instead when taking a shower. Does one have to be careful with chatitza (interposition), such as long toe nails?
A. Poskim permit using a shower for pouring the nine kavim of purification ( Minchas Yitzchak 4: 21,Yaskil Avdi 7: p. 387, Taharas Yom Tov 19, Chelkas Yakov 3: 61,, Shevet HaLevi 1:24, Halichos Olam p. 157, Yalkut Yosef 626, Minchas Oviv p. 202, and others, although some disagree Mishne Halochos 3: 1-7, 3: 23)
Shaarei Teshuva (O.H. 88: 4) quotes Maamar Mordechai that a chatzitza does not affect the purification of tisha kavim. Biur Halocho (88: 4) quotes a similar opinion from Sefer Hoeshkol and rules that it is not an interposition, unless it covers most of the body. See also Minchas Chinuch (180: 4).
Horav Shlomo Miller’s Shlit’a opinion is similar.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit’a