Soldered and brazed
This method requires the use of heat or flame to bring the copper tube and fittings up to the joining temperature so the filler metal can melt, flow into the capillary space between the tube and fitting, and solidify to create a strong, metallic bond. The main difference between the two methods is the filler metal used (solder or brazing filler metal) and the temperature required. Soldering takes place below 450 C (840 F); brazing occurs from 450 to 1080 C (840 to 1980 F). While extremely strong and robust, these methods are not commonly used for underground water services.

Flared joints
A mechanical joining method that does not require the use of heat or flame, this technique creates a metal-to-metal seal between the copper tube surface and the copper fitting. To make these joints, a special flare nut is installed on the tube end, which is then mechanically flared (expanded and formed into a conical shape) using a specially designed flaring tool. The flare nut is then used to draw the flared tube end onto the outer surface of the fitting using a threaded connection between the flare nut and the flare fitting. This creates a strong, easily installed metal-to-metal connection that can be disassembled if necessary. Flared joints are the most common joining type for underground water service lines.

Pack-joint compression joints
A mechanical joining method through which a flexible gasket is compressed (i.e. packed) between the outside surface of the tube and the inner surface of the fitting, without any working of the tube end. The body of the compression fitting is clamped to the outer surface of the tube to prevent lateral movement. The gasket is then compressed between the tube and body of the mating fitting to create a leak-tight seal between the gasket and tube and fitting surfaces. This type of joint is only commonly used in underground water services.

Roll-grooved joints
In this mechanical joining method, a groove is rolled into the end of the tube, which is then joined to a matched grooved fitting and connected using a gasket and clamp on the exterior of the assembly. Generally, it is only available for copper systems over 50 mm (2 in.) in diameter; it is not commonly used in underground construction.

Press-connect joints
For this mechanical joining method, a special fitting, containing an O-ring or gasket integral to the fitting, is mechanically pressed or crimped to the exterior tube surface using specially designed powered crimping tools. This results in deformation of both the tube end and the fitting, which creates a strong metal-to-metal joint, with a gasket to provide leak-free service. This joint is not commonly used for underground construction.

Push-connect joints
In this mechanical joining method, a special fitting, containing an O-ring or gasket and a metal grip ring integral to the fitting, is pushed onto the tube end by hand. No deformation of the tube or fitting is created—the grip ring prevents the tube from pulling out of the fitting and the gasket provides leak-free service. This joint is not commonly used for underground construction.