We have an Australian two speed upstairs. It is super miserly with water being designed for the outback. I haven't touched it since it was installed in 2002 and it's never clogged. Well, that's not quite right. Once my son did such a huge log that it bridged the trap. Nothing would make it pass. I got a shingle scrap and handed it to him and told him it was his problem to fix. He performed the surgery laughing all the way and all was well with the next flush.