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Verify Water Supply is Off — Drain the Line and Confirm Shutdown

Beginner

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How to Fix a Leak at a Faucet Supply Line Connection · Step 3 of 9

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After turning the shut-off valve, go to the filtered water faucet on the sink and activate it. This action will release any remaining pressure in the line and, more importantly, confirm that the water supply is successfully shut off. If water continues to flow, re-check the shut-off valve.

Goal: Confirm water is shut off and release pressure

  • This simple check prevents messy surprises and confirms that you have correctly operated the shut-off valve.
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FAQs

How long does this repair typically take for a beginner, and what's the real difficulty level?

This is a beginner-friendly project, usually taking 30-60 minutes once you have the right parts. The most challenging aspect is often working in tight, cramped spaces under the sink. Taking your time to ensure proper alignment and avoid cross-threading is key to success.

How do I know which new supply line to buy, especially regarding size and length?

Before purchasing, measure the length of your old supply line from end to end. Note the connection sizes: faucet connections are typically 1/2 inch FIP, and shutoff valve connections are commonly 3/8 inch compression. Bringing the old line to the store or taking a picture of the connections can help ensure you get an exact match.

I replaced the supply line, but it's still leaking. What should I check next?

First, ensure both ends of the new supply line are hand-tightened, then given an additional quarter to half-turn with a wrench – avoid overtightening. Check that the rubber washer (gasket) inside the supply line nuts is properly seated and undamaged. If the leak persists, the shutoff valve itself might be old and failing, or the connection point at the faucet could be compromised.

What if I can't turn off the water supply to my faucet, or the shutoff valve itself is leaking?

If the existing shutoff valve is stuck, leaking, or won't completely stop the water flow, you will need to turn off the main water supply to your entire house before proceeding. In such cases, or if you're uncomfortable with the main shutoff, it might be best to contact a qualified plumber, as replacing a main shutoff or a frozen fixture shutoff is a more advanced task.