standard toilet drain slope Home › Forums › Public Forums › Drainage & Sewerage › standard toilet drain slope This topic has 1 reply, 2 voices, and was last updated 24 years, 1 month ago by SylvanLMP. Viewing 1 reply thread Author Posts 13 Sep 2000 at 5:22 pm #278672 MasterPlumbersKeymaster What is the standard drop per foot for a toilet drain pipe to a septic tank. 13 Sep 2000 at 7:14 pm #299028 SylvanLMPParticipant 1/8″- 1/2″ per ft depending on local code. Most plumbers try for 1/4″ Author Posts Viewing 1 reply thread You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Log In