In his tzavaah, will, Rabbi Yehuda HaChassid wrote that one should not build bathing facilities (merchatz) in ones private home unless it is for public use. According to many authorities, even living in such a home is an issue. In a letter, the Rebbe Maharash of Lubavitch suggests very creative strategies to get around the problem of having a bathtub in a private home. Some poskim suggest that if there are a number of people in the family, it can be considered public use; others disagree with this leniency. In modern times when all private homes have showers or bathtubs, contemporary poskim say it is not an issue, and that the issur applies only to a facility with lots of steam. A similar idea is found in the above-mentioned letter of the Rebbe Maharash. Accordingly, having a sauna in a private home could be problematic. What about a mikvah for purification in a private home? There is a debate on this topic amongst various poskim, and many are lenient in the matter. Whereas the Rebbe Mahrash discusses the similarities between a merchatz and a mikvah in the above-mentioned letter, it is difficult to establish his position in the matter.