The answer to this question really depends on the situation, whether your landlord is making a reasonable effort to remedy the issue and how long it actually ends of taking. For the time being, I would suggest that you save your emails or letter correspondence requesting the repairs and consult an attorney if it drags on beyond a week.
This cannot property be answered without reading your lease.
Do you have a lease? If you do, there is often a paragraph in it which talks about repairs to be made by the landlord. Usually the paragraph will say that the tenant is responsible for giving the landlord immediately notice of anything that needs to be fixed in the apartment. the paragraph may also state the length of time in which the landlord agrees to fix the problem (or it may not).
If you have no written lease or your lease does not give a time-frame in which the landlord must make repairs, then you should, as soon as you know of a problem, write a letter to the landlord exlaining in detail what the proplem is, how long it has been broken, and the damage it is causing. Take pictures of the damage and how it is being caused and turn on the function in your camera or camera phone that show the date the picture was taken. When you write to the landlord, you should include an outside date on which you want the item fixed. The time you give to your landlord will not be binding, but it will help show how dangerous or important it is that the item be fixed. In your case, not being able to use the bathroom, I would have asked that it be fix in one or two days. If after the time period has passed and the landlord has not responded (expecially in an emergency situation) or has not fixed the problem, you need to write him another letter telling him that the problem has not beed repaired and what you plan on doing about that.
If the landlord has covenanted in the lease to repair, but does not fix the problem (assuming that the problem is material) , Tenant has 3 options: (1) Upon the landlord's failure of performance, the tenant can perform it at his own expense and deduct the cost of such performance from the amount of rent due and payable; or (2) the tenant can surrender the possession of the premises to relieve himself from any further payment of rent; or (3) he can retain possession of the premises and deduct from the rent the difference between the rental value of the premises as it would have been if the lease had been fully complied with by the landlord and its rental value in the condition it actually was. (this 3rd option is often difficult to formulate, but may be done if, for instance, an entire room is unusable becasue of what needs to be fixed).
When you decide on your course of action, write to your landlord and explain why his suggested solution was not acceptable and then tell him what you intend to do (withhold rent, adjust the rentdownward, or move out).
Everything said herein is subject to what may be contained in the lease which may contradict this answer in part, in which case, the lease controls. It is very important that you have an attorney read your lease and anaylze your situation before your taking further steps. I would be happy to do this for you if you want, or feel free to contact another real estate attorney.