Adjustable wrench
Use it for: To loosen and tighten compression nuts and hold the valve body steady.
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How to Replace a Hose Bib Shutoff Valve Compression Supply Line
To replace a hose bib shutoff valve compression supply line, shut off the water, relieve pressure, remove the old line with two wrenches, install the new line without twisting it, then turn the water back on and check closely for leaks.
This repair is usually the right move when the supply line is dripping at the nut, corroded, kinked, or wet along the tubing itself. The job is straightforward if the shutoff body and nearby pipe are still solid.
Before you start: Match the line length, end sizes, and connection type before ordering.
Safety first
- Shut off the water fully before loosening compression fittings.
- Use two wrenches so you do not twist a valve or pipe inside the wall.
- Open the line slowly when restoring water to reduce sudden pressure on the new connection.
- Do not force corroded fittings if the connected pipe is moving or the wall pipe feels fragile.
Tools you may need
Second wrench or slip joint pliers
Use it for: To back up the valve or connected fitting so you do not twist the pipe in the wall.
Shop backup pliers
Bucket or shallow pan
Use it for: To catch the water left in the line when you disconnect it.
Find a drain pan
Rags or paper towels
Use it for: To dry fittings so you can spot a fresh leak during testing.
Shop shop towels
Tape measure
Use it for: To confirm the replacement line is the right length before installation.
Find a tape measureAs 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 part that failed
- Look at the hose bib shutoff area and dry everything with a rag.
- Turn the water on briefly if needed and watch where fresh water appears.
- If the tubing is split, corroded, kinked, or leaking from the line ends while the valve body itself stays dry, the compression supply line is the likely problem.
- Check that the shutoff valve body, the hose bib connection, and the exposed pipe are not cracked or badly rusted.
If it works: You have confirmed the leak or damage is coming from the supply line or its end connections.
If it doesn’t: If water is coming from the valve stem, valve body, wall penetration, or the pipe itself, this is probably not the right repair path.
Stop if:
- The shutoff valve body is cracked, badly corroded, or loose in the wall.
- The connected pipe moves significantly when touched.
- There is hidden water damage, mold, or rotted wall material around the valve area.
Step 2: Shut off water and relieve pressure
- Close the nearest upstream shutoff for this line. If there is no reliable local shutoff, turn off the home's main water supply.
- Open the hose bib or nearby faucet to relieve pressure and drain off trapped water.
- Place a bucket or shallow pan under the supply line connection.
- Wipe the area dry so the fittings are easier to handle and inspect.
If it works: Water flow has stopped and the line is depressurized.
If it doesn’t: If water keeps running steadily after the shutoff is closed, use the main shutoff before disconnecting anything.
Stop if:
- You cannot fully stop the water flow.
- The shutoff handle will not move or starts leaking heavily when operated.
Step 3: Remove the old compression supply line
- Use one wrench to hold the valve or fixed fitting steady.
- Use the second wrench to loosen the compression nut on one end of the supply line.
- Loosen the nut on the other end the same way, again backing up the fixed fitting so it does not twist.
- Pull the old line free and keep any ferrule or compression sleeve arrangement in mind so you can compare it with the new part.
- Measure the old line length and compare both end connections to the replacement before installing it.
If it works: The old supply line is out and you have confirmed the new line matches the basic length and connection style.
If it doesn’t: If a nut is seized, apply steady pressure and improve your grip rather than forcing the pipe to turn. If the replacement does not match, pause and get the correct line.
Stop if:
- A fitting begins turning inside the wall or the pipe starts bending instead of the nut loosening.
- Threads are stripped or a compression seat is visibly damaged on the valve or mating fitting.
Step 4: Install the new supply line
- Start each connection by hand first so the nuts thread on smoothly and do not cross-thread.
- Route the new line in a gentle curve without sharp bends, kinks, or tension.
- Hold the valve or fixed fitting with one wrench and tighten each compression nut with the second wrench until snug.
- Do not overtighten. Compression fittings seal by proper compression, not brute force.
- Wipe both ends dry once the line is installed.
If it works: The new line is installed straight, supported, and not twisted or kinked.
If it doesn’t: If a nut will not start by hand, back it off and realign it before tightening again.
Stop if:
- The new line is too short to reach comfortably or must be forced into place.
- A fitting will not thread on cleanly after careful realignment.
Step 5: Turn the water back on and check for leaks
- Close the hose bib or faucet you opened to relieve pressure.
- Slowly reopen the upstream shutoff or main water supply.
- Watch both ends of the new supply line as pressure returns.
- Run a dry paper towel around each compression nut and along the tubing to catch even a small seep.
- If you see a slight drip at a compression nut, tighten that nut a little more while backing up the fixed fitting.
If it works: The line holds pressure and both ends stay dry during the first leak check.
If it doesn’t: If a connection still seeps after a small retightening, shut the water back off, relieve pressure, and inspect for misalignment or the wrong part.
Stop if:
- Water sprays from a fitting or the leak gets worse when pressure returns.
- The valve body or nearby pipe starts leaking once the system is pressurized.
Step 6: Verify the repair in normal use
- Open and close the hose bib several times to put the line through a normal use cycle.
- Check the supply line again while water is flowing and again a few minutes after shutoff.
- Feel around the fittings and the area below them for any slow drip.
- Recheck once more later the same day if the area was previously wet or hard to see.
If it works: The hose bib works normally and the new supply line stays dry during use and after shutoff.
If it doesn’t: If moisture returns, dry the area and pinpoint whether it is from a connection, the valve itself, or another nearby plumbing part.
Stop if:
- A slow leak keeps returning after careful retightening.
- You find water coming from inside the wall or from a different damaged plumbing component.
Replacement Parts
Find a hose bib shutoff valve compression 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
- Both ends of the new supply line stay dry under full water pressure.
- The line is not kinked, stretched, or rubbing sharply against nearby surfaces.
- The hose bib opens and closes normally without fresh drips at the supply line.
- No moisture returns after the fixture has been used and then left off for several minutes.
FAQ
Do I need thread tape on a compression supply line?
Usually no. Compression fittings seal at the ferrule or built-in sealing surface, not on the threads. Thread tape is generally not used unless the replacement part specifically calls for it.
How tight should the compression nuts be?
Tight enough to seal without crushing or distorting the connection. Start snug, then test under pressure and tighten a little more only if needed while holding the fixed fitting with a backup wrench.
Can I reuse the old compression parts?
It is better to use the new line and the connection parts that come with it, if included. Reusing worn compression pieces can lead to repeat leaks.
What if the new line is slightly longer than the old one?
A little extra length is usually fine if the line can make a smooth curve without kinking or rubbing. It should not be forced into a tight bend or sharp loop.
Why does it still drip after I replaced the line?
The most common causes are a mismatched connection, a crooked or cross-threaded nut, not enough tightening, overtightening that damaged the seal, or a leak that is actually coming from the shutoff valve or nearby pipe instead of the line.