Replace Supply Lines (Toilet or Faucet)

Stop drips and prevent bursts by swapping old, brittle lines for new braided stainless lines.
Difficulty: Easy
Success Rate: 90%
Cost: $10 - $25
Estimated Timeline: 30–60m
Turn Off Water: Yes
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Tools Needed:

  • Adjustable wrench or channel-lock pliers

  • Small bucket or towel

  • Flashlight

  • Utility knife or scissors (to trim tape labels)

Materials / Parts:

  • Braided stainless supply line(s) matched to fixture (toilet or faucet)

  • New cone/gasket washers (usually preinstalled)

  • Teflon (PTFE) tape (only for male NPT threads—skip on compression)

Safety Warnings:

  • Do not overtighten compression nuts—hand tight plus a small turn.

  • If the shutoff valve leaks or won’t turn, stop and call a pro.

  • Support the valve and the faucet/toilet shanks while tightening to avoid twisting.

Test & Verify:

  • Dry all joints; wait 2–3 minutes and recheck for moisture.

  • Run the faucet or fill/flush the toilet and verify no drips.

  • Confirm hose has no kinks and doesn’t rub sharp edges.

Cleanup & Disposal:

  • Wipe fittings dry; remove the bucket/towel.

  • Dispose of the old hose(s); coil the new hose gently to avoid strain.

  • Leave a paper towel under the joints for an hour and check for spots.

Pre-Checks:

  • Identify connection types and sizes (common: 3/8″ compression at the stop; 7/8″ ballcock at toilet; 1/2″ IPS or 3/8″ compression at faucet).

  • Verify shutoff valve closes fully; place a bucket/towel beneath.

  • Check clearance to ensure gentle hose bends without kinks.

  • Confirm line length with a tape measure (allow soft curves, no tight radius).

Step-By-Step Instructions:

  1. Close the shutoff valve clockwise. Open the faucet or flush the toilet to relieve pressure.

  2. Place a bucket/towel under the valve and connection.

  3. Loosen and remove the old supply line at the valve, then at the fixture. Catch any drips.

  4. Clean the mating surfaces and threads; remove old tape or mineral crust.

  5. If the valve side is male NPT (rare at stops), wrap PTFE tape clockwise 3–4 turns. Do not tape compression threads.

  6. Hand-thread the new supply line onto the fixture shank first (toilet fill valve or faucet tailpiece). Snug gently with a wrench—do not force.

  7. Hand-thread the other end onto the shutoff valve. Align the hose in a smooth curve without kinks, then snug the nut with a wrench.

  8. Slowly open the shutoff valve while watching both ends of the line.

  9. If a joint weeps, nudge alignment and tighten the nut an additional small turn.

  10. For faucets with two lines, repeat for the second side and test hot and cold.

When to Stop & Call a Pro:

  • Shutoff valve won’t close or begins to leak at the stem.

  • Supply connections are corroded, cross-threaded, or spin with the nut.

  • Persistent seepage after correct tightening and alignment.

Common Mistakes:

  • Overtightening compression fittings and crushing the cone washer.

  • Using PTFE tape on compression threads (not needed and can cause leaks).

  • Choosing the wrong length and forcing a kinked bend.

  • Twisting the faucet/toilet shank while tightening.

Troubleshooting:

Q: Slow drip persists at the valve connection.
A: Loosen, realign, hand-thread carefully, then snug in small increments.

Q: Hose kinks when installed.
A: Use a longer line or reroute with a wider curve; never force a tight radius.

Q: After replacement, water hammer occurs.
A: Verify valve is fully open; consider mini-arresters at quick-closing fixtures.

Q: Slight seep only during flow.
A: Tighten the suspect connection a small additional turn; confirm the cone seats squarely.