I've been using it for about four years now and flush it. Lately I've been hearing gurgling noises from the toilet when I run water in the sink, or even when the dishwasher was running last night! I'm thinking the pipes are probably getting clogged. I'm going to put some Liquid Plumber down the sink and tub drains and see if it makes any difference. I really don't want to have to stop flushing but I don't want to have to pay a plumber to clean all my pipes out either!