Waste Pipe Sizing Home › Forums › Public Forums › Drainage & Sewerage › Waste Pipe Sizing This topic has 3 replies, 4 voices, and was last updated 23 years, 10 months ago by SylvanLMP. Viewing 3 reply threads Author Posts 30 Jan 2001 at 2:18 pm #278880 adam typinski What are the rules dictating waste pipe sizing? I have to run a kitchen sink drain close to 25 feet. Is 2″ sufficient? 31 Jan 2001 at 8:53 am #299504 GuestParticipant No you should be using 100mm pipe until you are above floor level then you can reduce down to 50mm 4 Feb 2001 at 4:29 pm #299505 Wallingford Plm+HtgParticipant In Ct 2″ pipe is fine for a kitchen drain.Oversizing is not good as you will reduce the scouring action. 4 Feb 2001 at 8:30 pm #299506 SylvanLMPParticipant Yes 2″ would be fine for sink drainage REGARDLESS of lenth The waste line is sized by total Fixture units connected (FU) and also by the pitch of the piping. Author Posts Viewing 3 reply threads You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Log In