How long should I wait for a landlord to get back to me before I call a plumber myself?

The landlord is responsible for repairs in your home so that he provides a habitable property. A slow draining shower will probably not make your property uninhabitable (unfit for human habitation). What most people don't know, is that a tenant is also responsible for certain types of repairs of the property. These usually encompass common areas, hallways, or amenities like refrigerators or washing machines. What is tricky about your situation is that it doesn't really fall neatly into either category. A slow draining shower, while annoying, does not make the property unfit for human living. However, the complete lack of a shower (or toilet, or running water) might make a property uninhabitable. Your plan of repairing and deducting the cost of repairs from rent is commonly referred to as "self-help" and is not favored by many judges. While it does exist as an option, it should be a last and final resort, (and while i don't mean to undermine your problem, should also be for a more serious condition of the property than a slowly draining shower). I would first look to the lease agreement and see if it speaks to what duties you have as far as repairs and maintenance of the property, it may be written in the lease that things like this fall completely on you. Continue to try and contact your landlord. Possibly he/she will reimburse you for the plumber. And remember, "self-help" should be a last resort. Ideally, I believe contacting a local attorney or the SF Tenants Union would be appropriate. Their website is below. http://www.sftu.org/