The Shulhan Aruch (Orah Haim 544) rules that "Sorcheh Rabim" – literally, "public works" – are permitted on Hol Ha’mo’ed. Examples include road repairs and marking graves so Kohanim can avoid them. The Mishna Berura (Rav Yisrael Meir Kagan of Radin, 1839-1933) explains that on Pesah people have the time to address public needs and they therefore should not be delayed until after the holiday.
The Sha’areh Siyun addresses the case of a public bathhouse in need of repairs, and rules that it may be repaired during Hol Ha’mo’ed, as this is an important public need. Private baths, however, may not be repaired during Hol Ha’mo’ed, even in a non-professional manner, since this does not qualify as a vital need.
Seemingly, then, if a person’s bath or shower in his home is not functioning, he would not be allowed to hire a plumber to do repairs, since this is a private bath. However, the later authorities note that nowadays, when everybody has a bath in his home and bathes regularly, it is very difficult for people to be without a functioning bath, and repairing it would thus be considered necessary for the holiday. As such, the work Hol Ha’mo’ed Ka’hilchato (chapter 7, p. 86), citing Rav Moshe Stern of Debrecyn, rules that if one does not have a functioning shower or bath in his home, he may hire a non-Jewish plumber to make the necessary repairs, even if this entails professional work. This applies as well if repairs are needed to the faucets or boilers.
If, however, one’s shower is broken but another one is available in the home, he may not have repairs done.
A Jewish worker may be hired for repairs on Hol Ha’mo’ed only if they do not require professional work. The exception to this rule is the case of a problem which is causing damage, such as a leak. In such a case, one may hire a Jewish plumber even to make professional repairs.
Summary: If one’s only shower or bath is broken, he may hire a non-Jewish plumber for professional repairs. A Jewish worker may be hired only for repairs which do not entail professional work, unless the problem can cause financial damage, such as in the case of a leak.
