What size O-Rings Home › Forums › Public Forums › General Plumbing › What size O-Rings This topic has 1 reply, 2 voices, and was last updated 18 years, 4 months ago by Retired plbg1. Viewing 1 reply thread Author Posts 26 Nov 2005 at 8:25 pm #277723 duffy pastore Can someone inform me what size 0-Rings go into domestic internal house taps. Are they 8mm or 8.5mm and do external garden taps use they same size.Everytime I go to a hardware store they give me conflicting answers.Thanks Brian …Handyman Brian 27 Nov 2005 at 9:36 pm #296984 Retired plbg1Participant They sell them on a card here some are fat and some are skinny, buy a pack and see which one you need. Art retired plbg 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