i have been in this house for over 3 years and never had this problem. first off let me tell you about the set up in my house, i have two bathrooms the small one has just a toilet and a sink and the other is a full bathroom. the problem i am having is in the small bathroom when i flush the toilet it fills up and there is a gurgling noise in the sink and about 30 seconds later the toilet drains, and in the big bathroom when i flush the toilet it flushes full speed and it sends the gurgling noise to the small bathroom.....I dont know what could be the problem so please help me with this!