0framistan 7 years ago ReplyUpvoteI had that problem once. Eventually i discovered a plastic fork was lodged in the toilet. The fork would not go around the "S" curve of the pipe. It allowed water to pass, but slowed it down so it wouldn't flush properly. Things fall in there and family members might try to flush it away. Toothbrush or other item is likely stuck in the 'S" curved toilet pipe.