What you need to know about push-fit fittings
Nicolas Geoffroy, Ph. D., P.Eng.
Push-fit fittings, often known under the brand name SharkBite, are very popular due to their ease of use and versatility. They enable quick connections between different materials without the need for tools or heat. However, these fittings are more expensive than other options and are therefore typically used by DIY enthusiasts for small jobs or by plumbers for specific applications (e.g., very limited access).
That being said, push-fit fittings also often have a bad reputation, with many plumbers considering them to be unreliable and not durable. This article aims to dispel some of the myths surrounding them.
Firstly, push-fit fittings are used in pressurized water distribution systems to connect copper, PEX and CPVC pipes, and to facilitate transitions between different materials. To use them, you simply need to cut the pipe straight and deburr it before inserting it into the fitting up to the design depth. The retaining mechanism includes a retaining ring which grips the outer surface of the pipe to ensure a secure connection. The O-ring provides a watertight seal. Another feature of this type of fitting is that it can usually be disassembled by pressing an outer collar, which disengages the retaining ring.
Some Common Myths
Push-fit fittings are only temporary: False. These fittings are typically certified under ASSE 1061 for permanent installations;
Push-fit fittings should only be installed in accessible areas: False. Unless otherwise specified by the manufacturer, push-fit fittings are certified for use in inaccessible spaces, such as inside wall cavities;
Push-fit fittings cannot handle normal operating pressure: False. The ASSE 1061 standard requires fittings to withstand a minimum pressure of 100 psi at 180°F. These values exceed the maximum pressure permitted by the National Plumbing Code (80 psi) and the typical water heater temperature (140°F). In fact, many fittings are certified for much higher pressures (e.g., 300 to 400 psi);
Push-fit fittings are always at risk of leaking due to the presence of an O-ring: False. O-rings are widely used in many permanent plumbing applications and are generally durable. ProPress crimp systems, for example, also rely on similar O-ring seals.
To verify the long-term durability of push-fit fittings, we disassembled two pieces (a ½” cap and union) that had been installed in a home in Montreal for about 11 years. Both pieces were still watertight and showed no visible signs of deterioration. They were then cut lengthwise to inspect the internal components, particularly the O-ring. The O-ring is indeed the weakest component of this assembly system as it can deteriorate over time. However, upon inspection, it was found to be undamaged and clearly capable of maintaining a watertight seal for many years.
Common Causes of Failures
Although push-fit fittings are generally reliable, CEP occasionally investigates cases involving them. The main causes of failure that we have identified include the following:
- Improper installation: A poorly deburred pipe can damage the O-ring during assembly; contaminants on the pipe surface can lead to leaks; insufficient insertion of the pipe into the fitting can result in a weak connection;
- Freezing: Although they are relatively robust, push-fit fittings are often the most vulnerable components in a plumbing system. In the event of freezing, they are usually the first to fail. However, the root cause of the failure is the freezing, not the fitting itself;
- Low-quality push-fit fittings: As with many plumbing components, it is strongly recommended that you use products from reputable brands and avoid off-brand or generic alternatives, which often lack adequate quality. Failures due to manufacturing defects are typically linked to the dezincification of the brass body or the deterioration of the internal plastic mechanism.
Figure 1 – Freezing of a push-fit fitting
Figure 2 – Low-quality push-fit fitting
In summary, SharkBite push-fit fittings are reliable products that can be used to create long-lasting watertight connections. Although they are easy to install, it remains essential to follow the manufacturer’s instructions to avoid potential failures. Finally, purchasing certified, name-brand fittings is key to minimizing the risk of malfunction.
If you have any questions or files involving push-fit fittings, don’t hesitate to consult the materials experts at CEP Forensic.