I was so eager to answer some of your questions that I see that I didn't pay attention to the last part of your inquiry.
You were concerned about having only one bathroom. The procedure will most likely be that after the treatment, you will be told to try to hold it for two hours, or as long as you can up to that time. For the next four hours or so, every time you urinate, they ask that you add a cup of bleach to the toilet and wait a few minutes for it to kill any residual BCG before flushing. After that time, you can clean the toilet as usual and everything should be clear.
You will not want your grandchildren around during this time, and you definitely won't feel like having friends over! For several hours after the treatment you will have urgency and probably feel like you have to go every five minutes!! You should drink a lot of fluids to help wash this through. There may be a bit of bleeding (the lining of the bladder is sloughing off a bit...this is what you want to happen.) And you may feel crampy.
For a day or so after you may feel extra fatigued. All these symptoms mean that the stuff is WORKING. And these minor side effects get a bit more noticeable with each additional treatment. The purpose of this treatment is to REALLY kick up your body's immune response in the bladder, so it becomes a bit more sensitive each time it is challenged. If the symptoms become too uncomfortable, your urologist can reduce the dose. By the time I finished I was on 1/3 the original dose; even down to 1/10 has been used successfully.
Here is a very good source to read up on BCG therapy:
www.bcgoncology.com/treatment/bcg.html
Remember, that ALL the possible side effects are noted. Very few people have these. As you know, every drug has side effects and, if we read them all, we probably would be afraid of taking anything!
Again, ask all the questions you can think of....there are MANY of us here who have done this very successfully.
Sara Anne