Gurgling in pipes after all toilets flush
What causes pipes to make a moaning/gurgling sound after flushing toilets? And how can I fix it? We live in a 107-year old house and have lived here for the past three years. About a month or so, we started to hear our pipes after flushing the toilets. You can hear the sound from one of the bathrooms, which has an inexplicable drain in the floor (the primary source of the noise). It basically sounds like you can hear the water/waste gushing down the pipes. The sound starts after the toilet bowl has completely emptied. We hear the noise in the same place (which is on the second story and the only place you hear it) regardless of whether we are flushing a toilet on the first, second, or third stories. We have four toilets and it makes the sound for every single one (making the most sound with the third story, presumably because it has further to go). Why would this suddenly start happening and how can we determine what's gone wrong and fix it? THANK YOU!