May one launder his clothing on Chol Hamoed if they all became dirty?
The general rule: It is forbidden to launder clothing on Chol Hamoed. This applies even if one is doing so for the sake of wearing the clothing during the Moed and certainly if one is doing so for the sake of wearing the clothing after the Moed. This applies even if all of one’s clothing have become dirty. This applies even if one made sure before the Moed to launder all of his clothing. Nonetheless, the following exceptions apply:
If one only owns one pair: If one only owns one pair of clothing [such as one jacket, or Kapata, or one pants or one shirt] then if the article of clothing became dirty, it may be laundered during then Moed. [This applies even if one did not launder the clothing before the Moed.]
Clothing that are changed daily: The above prohibition only applies to clothing that are customarily worn for more than one day at a time. However, all clothing which are changed on a daily basis due to becoming dirty [such as due to sweat and the like] may be laundered during Chol Hamoed [if one does not have any more of that clean clothing remaining]. [Hence, one may launder underclothing, such as socks, undershirt, underwear if they are all dirty, and one is accustomed to change them daily. Likewise, in hot climate areas where it is accustomed to change one’s shirt daily due to the sweat, one may launder his shirt if they are all dirty. Nonetheless, despite the above allowance, one is to be particular to launder all of his clothing before Yom Tov in order to have enough clothing to last throughout Yom Tov, without needing to launder it. If one did not do so, some Poskim rule he may not launder the clothing during Chol Hamoed, although the majority of Poskim side to be lenient.]
It is forbidden to launder clothing on Chol Hamoed even if all of one’s clothing have become dirty, unless one only owns one pair of that clothing [such as one jacket, or Kapata, or one pants or one shirt] or the clothing is changed on a daily basis due to becoming dirty [such as due to sweat and the like] and one does not have any more of that clean clothing remaining. Hence, one may launder underclothing, such as socks, undershirt, and underwear if they are all dirty, and one is accustomed to change them daily.
When laundering clothing that are changed daily, how many clothing may be laundered at a time?
One may only launder as many clothing as he needs, such as a single shirt. Some Poskim interpret this to mean that one may launder as many clothing as he will need until the end of Yom Tov. Others however rule that one may never launder more than one clothing at a time, per day. Practically, in today’s times that laundry is done using a machine, and there is no extra work involved in washing more than one necessary garment at a time, it is permitted to wash simultaneously all the clothing that will be needed until the end of Yom Tov, if te clothing are changed on a daily basis.
If one’s clothing is dirty to the point that it is unwearable in public, may he launder the clothing on Chol Hamoed, even if it is not changed daily, and one has more than one pair?
If all of a certain article of clothing have become dirty to the point that they cannot be worn in public, and one is unable to purchase a new article of clothing, then it is permitted to launder the clothing during Chol Hamoed. This applies even if one owns many pairs of that clothing, and they have all become dirty beyond wearing. If however one has ability to buy new clothing, then he must do so, rather than launder these clothing.
May one wash his single Shabbos pants that became dirty?
If one does not have any other pants available that can be worn on Shabbos, then he may do so.
Is it permitted for one to wash a blanket on Chol Hamoed if he has no other blankets available?
If this is the only blanket one has for him to use it may be washed.
 Michaber 534:1; Mishneh Moed Katan 13b
The reason: The Sages prohibited laundering clothing during the Moed in order so one launders his clothing before Yom Tov and hence have clean clothing for the sake of Yom Tov. [M”A 534:1; M”B 534:1]
 M”B 534:1; Kaf Hachaim 534:1
 Tosafus Moed Katan 14a; Chol Hamoed Kehilchasa ibid footnote 5
 Bach 531; Chol Hamoed Kehilchasa ibid footnote 6
 Michaber 534:1; Rebbe Yochanon Moed Katan 18b; Beis Yosef 534 in opinion of Rosh, Rambam, and Rif; M”A 534:3; Mamar Mordechai 534:2; Chol Hamoed Kehilchaso 5:6; See Kaf Hachaim 534:11
Other opinions: Some Poskim rule it is forbidden to launder clothing on Chol Hamoed even if one only owns one pair. [Rabbeinu Peretz, brought in Tur 534; Bach 534; Derisha 534:2; See M”B 534:9 who seems to side with the astringent opinion; Rav SZ”A in SSH”K 66 footnote 240; Piskeiy Teshuvos 534:4 rules stringently]
 Implication of Michaber ibid; Tosafus Moed Katan 18a; Shita Leriy Miparish p. 54; Ritva Moed Katan ibid; Makor Chaim 534; Chemed Moshe 534; Divrei Menachem; Pischeiy Teshuvah 534; Kaf Hachaim 534:12; Chol Hamoed Kehilchasa 5:3 footnote 23
Other opinions: Some Poskim rule the allowance to launder a clothing if one only owns one pair only applies if one laundered the clothing before the Moed. [Implication of Tur 534, brought in Kaf Hachaim 534:12]
 Michaber 534:1 regarding hand towels, as explained in the Tur 534 and M”A 534:2 that this applies being that these clothing are changed daily, and thus it applies even if one has many clothing of that type that became dirty during Chol Hamoed; Elya Raba 534:1; Chayeh Adam 110:2; M”B 534:4; Kaf Hachaim 534:4; Beir Moshe 7:10 that this applies to all clothing that are changed daily in one’s current society
 Tosefes Chaim on Chayeh Adam 110:1; Shulchan Shlomo; Kaf Hachaim 534:2; Chol Hamoed Kehilchasa 5:12 footnote 18; Piskeiy Teshuvos 534:3 that even if one knows he will not have enough for the entire Moed, he may not launder if he still has a clean pair available
 Chol Hamoed Kehilchasa 5:11
 See Beir Moshe 7:10; Shraga Hameir 7:43-3; SSH”K 66:66; Chol Hamoed Kehilchaso 5:2; Piskeiy Teshuvos 534:3
 See Shraga Hameir 7:43-3 and Bier Moshe ibid; See however Piskeiy Teshuvos 534:4 that one may not launder shirts even if they are all dirty.
 Talmidei Hariy Miparish; Shraga Hameir ibid; Chol Hamoed Kihilchaso 5:13 and 20
 Implication of Michaber ibid; Tosafus Moed Katan 18a; Shita Leriy Miparish p. 54; Ritva Moed Katan ibid; Makor Chaim 534; Chemed Moshe 534; Divrei Menachem; Pischeiy Teshuvah 534; M”B 534:4; Kaf Hachaim 534:12; Chol Hamoed Kehilchasa 5:3
 Rama 534:1; Mordechai in name of Rav Avraham; Hagahos Ashri; Shita Letalmid Riy Miparish in name of Raavad
Other opinions: Some Poskim rule that if one owns two shirts and they both became dirty, then he may launder both shirts. [Rabbeinu Chananel Moed Katan 14; Maharitz Geiso 2:24; Chidushei Haran ibid; See Chol Hamoed Kehilchaso 5 footnote 20]
 Aruch Hashulchan 534:3; Implication of wording of some Rishonim, brought in Nispach to Chol Hamoed Kehilchaso p. 180
 Chol Hamoed Kehilchasa 5:12 footnote 49; Implication of wording of some Rishonim, brought in Nispach to Chol Hamoed Kehilchaso p. 180
 Minchas Yitzchak 8:50; Yabia Omer 7:48; Beir Moshe 7:32; SSH”K 66:64 and 68; Nispach to Chol Hamoed Kehilchaso p. 180; Piskeiy Teshuvos 534:5
 See Shemiras Hamoed Kehilchaso 14:5 footnote 11
 See Chol Hamoed Kehilchasa 5:24
 Chol Hamoed Kehilchaso 5:32