Adjustable wrench
Use it for: To loosen and tighten the supply line nuts at the shutoff valve and faucet connection.
Shop adjustable wrenchesKitchen sink plumbing
How to Replace a Kitchen Sink Faucet Supply Line
If water is dripping from the faucet supply connection, the braided line is kinked, corroded, or won’t seal after tightening, replacing the kitchen sink faucet supply line is usually the right fix.
This is a manageable under-sink repair for many homeowners. The goal is to swap the old line without cross-threading fittings or overtightening them, then confirm the new connection stays dry under normal use.
Before you start: Match the line length, end sizes, and connection type before ordering.
Safety first
- Work with good lighting so you can see the threads and avoid cross-threading fittings.
- Keep a bucket and towels under the work area before disconnecting the old line.
- Do not overtighten supply line fittings. Too much force can damage threads, crush seals, or loosen the shutoff valve.
- If a shutoff valve will not close fully, use the main water shutoff before removing the line.
Tools you may need
Basin wrench
Use it for: Helpful if the faucet connection is tucked high behind the sink where a regular wrench will not fit well.
Shop basin wrenches
Bucket or shallow pan
Use it for: To catch the water left in the line when you disconnect it.
Find a drain pan or bucket
Old towel or rags
Use it for: To protect the cabinet floor and wipe fittings dry during leak checks.
Shop absorbent shop towels
Flashlight or work light
Use it for: To see the faucet shank, shutoff valve, and threads clearly under the sink.
Find an LED work lightAs an Amazon Associate I earn from qualifying purchases. Repair Riot may earn a commission at no extra cost to you.
Step-by-step fix
Step 1: Confirm the supply line is the problem
- Empty the area under the sink so you can see both ends of the supply line clearly.
- Dry the shutoff valve, the supply line, and the faucet connection with a towel.
- Run the faucet briefly, then watch for fresh water forming on the braided line, at the lower nut by the shutoff valve, or at the upper connection to the faucet.
- Check whether the line is visibly kinked, frayed, rust-stained, or bent sharply enough that it cannot sit naturally.
If it works: You have traced the leak or damage to the faucet supply line or its end connections.
If it doesn’t: If the water is coming from the drain, sprayer hose, faucet body, or shutoff valve itself, fix that part instead before replacing the supply line.
Stop if:
- The shutoff valve body is leaking or badly corroded.
- The cabinet floor or wall is soft, swollen, moldy, or shows hidden water damage that needs broader repair.
- You cannot identify where the water is actually coming from.
Step 2: Shut off the water and relieve pressure
- Turn the sink shutoff valve for the affected line clockwise until it stops. If you are replacing both hot and cold lines, shut off both valves.
- Open the faucet to relieve pressure and let the remaining water drain out.
- Place a bucket or shallow pan under the supply line connections and lay down a towel to catch drips.
If it works: Water flow from the faucet slows to a stop and the line is depressurized.
If it doesn’t: If the faucet keeps running steadily, the shutoff valve may not be closing fully. Use the main water shutoff before disconnecting the line.
Stop if:
- The shutoff valve will not close and you cannot safely shut water off at the main.
- The valve stem starts leaking heavily when you turn it.
Step 3: Remove the old supply line
- Use a wrench to loosen the lower nut where the supply line connects to the shutoff valve. Hold the valve steady if needed so you do not twist it in the wall or cabinet.
- Loosen the upper end of the line from the faucet connection. A basin wrench can help if access is tight.
- Pull the old line out and compare it to the replacement for length, end size, and connection style.
- Wipe both connection points clean so the new line can seat properly.
If it works: The old line is removed and the connection points are clean and ready for the new line.
If it doesn’t: If a fitting is stuck, apply steady pressure and improve your wrench position rather than forcing it sideways. Better access usually works better than more force.
Stop if:
- The faucet connection or shutoff valve threads are damaged, split, or badly corroded.
- The shutoff valve starts twisting loose from the pipe or wall when you try to loosen the nut.
Step 4: Install the new supply line by hand first
- Route the new supply line in a smooth curve without twisting or kinking it.
- Start the upper connection to the faucet by hand and turn it until it threads smoothly. Do not force it if it feels crooked.
- Start the lower connection to the shutoff valve by hand the same way.
- Once both ends are hand-threaded correctly, snug them with a wrench until secure. Do not overtighten; the goal is a firm seal, not crushed fittings.
If it works: The new line is installed with both fittings seated squarely and the hose routed without strain.
If it doesn’t: If the nut will not thread easily by hand, back it off and realign it. Cross-threaded fittings will leak and can ruin the connection.
Stop if:
- The new line is too short, too long to route safely, or has the wrong end connections.
- You cannot tighten the fitting without bending the faucet shank or stressing the shutoff valve.
Step 5: Turn the water back on and check for leaks
- Close the faucet if you left it open.
- Turn the shutoff valve back on slowly while watching the lower connection first, then the upper connection.
- Wipe both fittings completely dry with a towel.
- Run the faucet for a minute on both hot and cold as needed, then check again with a dry finger or tissue around each connection.
If it works: Both connections stay dry while the faucet is running and after the water is shut off.
If it doesn’t: If a fitting seeps, tighten that connection slightly and test again. Small adjustments are usually enough.
Stop if:
- A connection drips steadily even after careful retightening.
- Water appears from a different part such as the faucet body, sprayer hose, or shutoff valve.
Step 6: Make sure the repair holds in normal use
- Put the line in its final position so it does not rub on sharp edges or get pinched by stored items.
- Use the sink normally several times over the next few hours.
- Check the cabinet floor and both supply line connections again for any fresh moisture.
- Return items under the sink only after the area stays dry.
If it works: The cabinet stays dry through repeated use and the new supply line remains leak-free.
If it doesn’t: If moisture returns later, dry everything again and trace the exact source before tightening anything further.
Stop if:
- You find recurring moisture that is not coming from the new supply line.
- The cabinet shows ongoing water damage that needs repair beyond the line replacement.
Replacement Parts
Find a kitchen sink faucet supply line on Amazon
Match the line length, end sizes, and connection type before ordering.
As an Amazon Associate I earn from qualifying purchases. Repair Riot may earn a commission at no extra cost to you.
Verify the repair
- The faucet runs normally with no dripping at either end of the new supply line.
- The new line hangs in a gentle curve without kinks or twisting.
- The shutoff valve and faucet connection stay dry during and after use.
- The cabinet floor remains dry after several sink uses.
FAQ
Do I need to replace both hot and cold supply lines at the same time?
Not always, but it is often smart if both lines are the same age and style. If one has failed from age or wear, the other may not be far behind.
Should I use thread tape on a faucet supply line?
Usually no on the supply line nuts themselves. Most faucet supply line connections seal with a built-in washer or gasket, not with thread tape. Follow the sealing style of the line you bought.
How tight should the new supply line be?
Start both ends by hand, then tighten just enough to seal. Snug is the goal. If it leaks, tighten a little more and recheck rather than forcing it hard right away.
What if the old line is stuck and will not loosen?
Improve access first, use the right wrench, and hold the shutoff valve steady so it does not twist. If the valve or faucet connection is starting to deform or move, stop and address that problem before continuing.
How do I know I bought the right replacement line?
Match the connection type at both ends, the thread size, and the length. The line should reach without stretching tight or looping into a sharp bend.