I need some Plumber advise BIG TIME! Long story short, my brother and me purchased a second floor condo to renovate and flip. During our demo, we left the trap pipes in the bathrooms open. According to our condo association, water came out one of the trap pipes from the condo above us and caused a leak into the downstairs condo which we are responsible for. This does not sound right. I've never heard of water traveling up and out the trap pipe unless there is an underlying blockage somewhere down the line. Any help would be appreciated! 2nd post, didn't get a definitive answer from a plumber first time around. Thanks!!