What should we do if we just moved into a house with apparent water damage in spare bathroom, which we were told would be repaired before we moved in?

If you can show that you were told in writing that the repairs would be done before you moved in and they were not, then the landlord is in breach of contract and you could sue him for compensation reflecting the impairment of your use of the space. You could also potentially get out of the lease if you wanted, if the plumbing problems, etc. are severe enough.

Without a written agreement, you would have to rely on the implied warranty of habitability, or the requirement that the premises be fit for its intended purpose and habitable. The problem is, this warranty only affects *habitability,* so conditions that may be unattractive or nuisances (visible water damage; an annoying dripping leak; etc.) but which don't affect the ability to live there and use the space do not violate the warranty. You have no recourse for non-habitability conditions without some written agreement about making the repairs.

If the conditions do affect habitability, if the landlord has not at least scheduled/arranged for repairs after two weeks, you are getting close to when you could repair yourself--but again: only things that affect habitability--or potentially without some rent for habitability impairment. You should give the landlord further notice, in writing (send some way or ways you can prove delivery) and another 5 or so business days after receipt of notice to at least make arrangements; if he still doesn't do anything, you may then be able to repair and deduct the cost of the habitability-related repairs, or else withhold a portion of rent.