Besides 1/2" MIP, which is another popular hot and cold water line connection type?

• A. 1/4 inch OD compression joints
• B. 3/8 inch OD compression joints
• C. 1/2 inch copper tubing
• D. 1/2 inch NPT thread

Answer: (B)

Understanding common residential water line connections helps you pick the right fit for fixtures. Besides a 1/2 inch MIP threaded connection, a 3/8 inch outside-diameter compression connection is a very popular option for hot and cold supply lines. It uses a compression nut and ferrule that, when tightened, squeeze the tubing and seal against the fitting without any soldering or heat. This makes it quick to install and easy to disconnect for service, which is why it’s widely used on fixture supply lines and angle stops. The size is tied to the tubing’s outer diameter, so 3/8" OD is a standard, convenient choice for many faucet and valve connections.

Other choices are less typical for this common role: 1/2" copper tubing refers to the material/size and is usually joined by soldering or compression cans, not a single, standard “connection type” by itself; 1/2" NPT threads are pipe-thread connections that aren’t as common for quick, solderless fixture supplies.