I am at a loss with my hall bathroom toilet. When it is flushed, I can go into the basement (where the pipes are) and listen to the water rush down. As the toilet is filling, I can still hear a rush of water going down the pipes. Typically, the tank fills and I hear the water slow and stop. This has gotten progressively worse, to the point where I'm hearing water constantly going down the pipes, and the toilet runs occasionally. It currently has its water shut off because of the increased water bill. I replaced all of the "guts" in the tank, and upgraded to a more expensive flapper. The new flapper didn't change anything. The trickling noise doesn't come from the tank, it comes from the bowl. Also, I don't know if this is a coincidence or not, but the other toilet in the master bath (toilets sit back-to-back with a wall between them) sometimes has tiny bubbles clinging to the bowl, just under the water line.