Combined with a passive float valve, the system pretty much runs itself. Watch [Billy] give a tour of his system and valve design in the video embedded below.

Combined with a passive float valve, the system pretty much runs itself. Watch [Billy] give a tour of his system and valve design in the video embedded below.

The float, the flapper, or the fill valve are the most likely causes of a toilet running continuously. You can perform easy tests like monitoring water movement to help identify the cause.