Use plumber’s tape only when the fitting manufacturer specifies thread seal tape for compatible threads that seal along the thread. Do not use it where a washer, gasket, O-ring, compression olive or flared face forms the seal. Visible threads alone do not mean tape is required.
Connections that should not be taped
Check where the fitting seals rather than assuming its threads create the seal.
| Connection type | Where the seal forms |
|---|---|
| Washer or gasket fittings | A washer or gasket is compressed against a smooth mating face. The threads provide clamping force. |
| O-ring fittings | The O-ring seals against a specified surface or inside the fitting body. |
| Compression fittings | The nut compresses an olive against the pipe and fitting body. Tape does not belong on the nut threads or beneath the olive. |
| Flare fittings | Two shaped faces seal when the threads draw them together. |
| Non-threaded joints | Solvent-welded, soldered, crimped, press-fit and push-fit joints use their designated joining method or internal seal. The guide to how plumbers seal PVC pipe explains why the joint type controls the product used. |
Some fittings combine threaded and gasket-sealed components. Identify the sealing point from the fitting design and manufacturer’s instructions. If it remains unclear, have a licensed plumber assess it rather than experimenting with tape.
What about a refrigerator water line?
Many refrigerator hoses and water lines seal with a washer, O-ring, push-fit seal or compression connection, so thread tape may be unsuitable. Follow the appliance and fitting manufacturer’s instructions for the exact connection. Do not add tape to a joint that is designed to seal on another surface.
Connecting an appliance to a correctly installed, accessible stop tap is different from adding or altering drinking-water pipework. New valves, fixed pipework and regulated plumbing work should be completed by a licensed plumber.
When tape cannot stop a leak
Plumber’s tape cannot repair crossed, badly worn, damaged or mismatched threads. It also cannot fix a cracked fitting, distorted olive, failed O-ring, worn washer or damaged sealing face. These faults require correct assessment and replacement.
Adding tape may obstruct proper thread engagement or conceal the actual defect. Do not keep adding tape or tightening a leaking connection, as overtightening can damage the fitting. Isolate the water where safe and arrange an assessment if the leak persists, the fitting is concealed or the sealing method is uncertain. If water is escaping rapidly or threatening electrical equipment, check when a plumbing leak is an emergency.
Gas and specialised services
Do not use generic PTFE tape on gas or another specialised service unless the tape and installation method are expressly approved for that application. Similar threads do not make gas and water fittings interchangeable. Gasfitting in NSW must be performed by an appropriately licensed gasfitter.
If you suspect a gas leak, avoid flames, sparks and electrical switches. Leave the area and call your gas distributor’s emergency number from a safe location. Call Triple Zero (000) if there is immediate danger.
For an unidentified fitting or persistent water-line leak, contact Fixed Today for help from our licensed Sydney plumbers. We can identify the sealing method and repair the connection without masking the real fault.