That’s a great DIY project! Understanding the fittings is key to a leak-free connection.
Here is a breakdown of the typical fittings you’ll encounter under a kitchen sink, followed by videos to demonstrate the process.
💧 Kitchen Sink Water Supply Fittings
The supply lines (hoses) for a kitchen faucet generally need to connect two points: the Faucet Shank (the bottom of the faucet where the water lines come out) and the Shut-Off Valve (the valve attached to the pipe coming out of the wall or floor).
The most common fitting types you will see are compression fittings or threaded fittings, often using flexible braided supply lines.
1. Faucet End Connection
- Integrated Supply Lines: Many modern faucets come with the supply lines already attached to the faucet itself. The ends of these integrated lines usually have a standard compression nut (most commonly 3/8-inch compression or sometimes 1/2-inch threaded) designed to connect directly to the shut-off valve.
- Faucet Shank: If your faucet does not have integrated lines, the connection point will typically be a 1/2-inch Male Pipe Thread (MIP) shank, to which you attach a separate supply hose.
2. Shut-Off Valve Connection
This is the connection to the valve coming out of the wall/floor, and it’s where you’ll typically use a compression fitting for the water supply hose.
| Standard Sizes | Connection Type | Common Use |
| 3/8-inch Compression | Compression Nut | Most common size for kitchen and bathroom sink supply lines connecting to the shut-off valve. |
| 1/2-inch Compression | Compression Nut | Used for faucets that require a higher flow rate. |
Important Note: Flexible supply hoses (like braided stainless steel) have a built-in gasket/washer in the nut that screws onto the valve, creating the seal. When using these, you do not need the separate plastic ferrule and brass nut that sometimes come with the shut-off valve—only the hose itself.
Instructional Videos for Water Supply Connections
I’ve found a few helpful videos that demonstrate the process of connecting the supply lines, often including replacing the old shut-off valves as well.
| Video Title | Focus | Link |
| How to Replace A Compression Shut Off Valve & Faucet Supply Lines | Shows replacing the shut-off valve and connecting new flexible supply lines to the valve and the faucet. | Watch Video on YouTube |
| How to Select a Water Connection for your Faucet or Toilet | Explains how to select the correct supply line based on the connection type of your faucet (pigtail, threaded shank, or integrated lines). | Watch Video on YouTube |
| How to Install Shutoff Valves | Focuses on installing different types of shut-off valves (compression, push-to-connect) and then attaching the supply lines to them. | Watch Video on YouTube |
Pro Tip: Always shut off the main water supply to your house before starting any plumbing work to avoid leaks and damage.