Plumber's Tape (PTFE Tape)
Plumber's tape — officially called PTFE tape (polytetrafluoroethylene) and commonly called Teflon tape — is a thin, white, non-adhesive tape wrapped around threaded pipe fittings before assembly. It fills microscopic gaps in threaded connections, creating a leak-free seal on pressurized supply lines.
How to apply plumber's tape correctly:
- Start at the first thread of the male fitting
- Wrap clockwise when looking at the end of the pipe (same direction you'll tighten the fitting)
- Apply 2–3 wraps, stretching the tape slightly so it seats into the threads
- Tear the tape and press the end flat
- Thread the fitting on by hand first, then tighten with a wrench
Wrapping the wrong direction is the most common mistake — if you wrap counterclockwise, the tape bunches and shreds as you tighten, defeating the seal entirely.
PTFE tape colors and uses:
- White — standard, for water supply lines (NPT threads)
- Yellow — thicker, rated for gas lines (do not substitute white on gas)
- Pink — rated for potable water supply with NSF 61 certification
- Blue/Green — oxygen lines and specialty gases
PTFE tape vs. pipe dope (thread compound): tape is cleaner and easier for DIY use. Pipe dope (a paste) provides a stronger seal on older, coarser iron pipe threads and in high-vibration applications. Professional plumbers often use both together on critical connections.
A roll of standard PTFE tape costs $1–$3 and is one of the most used items in a plumber's kit.