The Ultimate Guide to Drain Connections

Slip joint connections are the most common and versatile drain connections found in residential plumbing systems. They consist of two pipes, one with a smooth end and the other with a threaded end, connected using a slip joint nut and a rubber or plastic washer. The washer creates a watertight seal, while the slip joint nut allows for easy adjustments and disconnections.

Slip joint connections are ideal for connecting sink traps and tailpieces, as well as tubular waste arms in kitchen and bathroom sinks.

Compression connections are similar to slip joint connections but utilise a ferrule, a small brass or copper ring, to create a watertight seal. The ferrule is placed over the pipe, and a compression nut is tightened around it, compressing the ferrule against the pipe and fitting.

Compression connections are often used in water supply lines and shut-off valves but can also be found in some drain applications. They are suitable for areas where disconnection or maintenance may be required, as they provide a secure, leak-free connection that can be easily taken apart.

Hub connections, also known as socket connections, involve joining pipes by inserting the smaller pipe’s end into a larger, bell-shaped pipe or fitting. The connection is sealed with a solvent cement, which chemically fuses the pipes together, creating a permanent, watertight bond.

Hub connections are commonly used for PVC and ABS drain, waste, and vent (DWV) systems. They are ideal for underground and concealed plumbing installations, as they provide a long-lasting, leak-free connection that requires minimal maintenance. However, they’re not suitable for applications requiring frequent disconnections or adjustments.

No-hub connections, also known as shielded couplings, are used to join cast iron, PVC, or ABS pipes without the need for a hub. A no-hub connection consists of a stainless steel coupling, tightened around the pipes using stainless steel clamps, and a neoprene gasket that creates a watertight seal between the pipes.

No-hub connections are often used in commercial and industrial settings where heavy-duty, corrosion-resistant connections are required. They’re also ideal for connecting pipes of different materials, such as joining PVC pipes to cast iron pipes in retrofit applications.