Once you've done all of the above, it's time to review local laws and policies. Depending on the area or state you live in, they may be different, but generally, as stated above, the negligent party is responsible for the damages. Go further: what about your condo insurance? How good is your water damage coverage in your policy if you end up shouldering it? Can you afford your deductible, and will your insurer cover the rest? All of these questions are important to ask when dealing with this kind of trouble. By talking with the building manager or owner and contacting your insurer, you should be able to come to a satisfying resolution as long as there was no negligence at your fault. Do your best to mitigate damage and show the claims adjuster what happened. Try to get it covered. And make sure you know everything you can about your case.