Vacated Vacation invokes the following three laws.
1. One is absolved from paying for unintentional indirect damages [Choshen Mishpat 386, Imrei Yosher].
2. If the seller can easily repair or replace the defective part (without adversely effecting the merchandise), the customer can only demand a repair or replacement part [Choshen Mishpat 232: Sma 2].
3. At times, certain defects in a merchandise can render the product unfit for a specific clientel's usage, but for others the product remains functional. When it is impossible to prove the clientel to which the consumer belongs, we respect the status quo and leave the merchandise and money in their respective jurisdictions [Choshen Mishpat 232: 23].
Application
The landlord unintentionally indirectly caused the vacationers a loss. Thus, the landlord is absolved from paying for their stay at the Dan Panorama.
Objectively, a backed up drainpipe can be fixed. As such, a renter should be required to remain in the house and simply have the landlord care for the leak in a timely and efficient fashion (and perhaps subtract rental money for the inconvenience).
However, there is reason to assume that the short term vacationers intended upon renting a hassel free living quarters. As such, dealing with a stuffed up drainpipe in a foreign country does not meet the descripton of the "sale". The situation cannot be fixed; and as such, the renter may leave and need not pay for the remainder of the days reserved.
As to exactly how much bother the renter was initially willing to endure, upon the "deal's consummation" is subjective and will be difficult to prove. As such, when doubts arise as to whether or not confering with the landlord and dealing with arranging for a plumber to repair the drain in a timely fashion is within the renter's inititional reasonable expectations, we would have to respect the status quo.
Practically speaking, if it would be able to be fixed in a timely fashion, the landlord would keep the deposit, but we could not obligate the renter to pay for the rest of the days so long as we cannot prove that they were initially willing to rough it for a few hours if need be.
We can assume that the vacationers wished to rent the apartment for a ten day bloc and did not wish to move their belongings from place to place during their stay. As such, we canot obligate them to return to the original apartment even after the landlord repairs the leak.
Dayan Chaim Kohn; Dayan K'hal Adas Yeshurun, Rav Gerrer Shteibel, Rabbnical Advisor Jewish Renaissance Center, Dean Business Halacha Institute