I propose to create a dating service "by the bath" :). So that anyone can place the address at home and during what period (14-21 days) he will be able to host guests :) and when he would like to visit (periods) - those families for which these periods match, will show each other. If during the placement you still write about yourself and those you would like to meet (well, there is the size of the bath, the presence of a jacuzzi, etc. :)) as well as the desired area (if the city is big), then you can choose friends. Albeit on day 21.
The target audience is likely only in Moscow under a million (well, minus children, homeless people, owners of boilers, etc.). Profit from advertising of saunas, boilers, etc. - targeting almost 100%.
PS Edited a bit - removed the news from Yandex. ')
UPD: You can make a bulletin board on this topic. For example, grandmothers (conditionally :)) will be able to take their bath for a couple of hours for xx rubles for those who do not have it (or simply do not have water) - why not a home business? If you build in the search based on the area of residence and home - you can show the results of ads on request (nearest) if there is no water in the requested house, or offer to place an ad for those who have water. Something like this :)