Symptoms
- Drip or spray at either end of the flexible supply line
- Wet cabinet floor tracing back to a specific line
- Leak worse when water is running
- Visible corrosion or mineral crust on the line
Likely causes
- CommonLoose connection nutNuts can loosen slightly from vibration over months or years.
- CommonWorn washer inside the connectionRubber or fiber washers harden and shrink with age.
- PossibleCracked or corroded supply lineBraided lines can develop pinhole leaks as the braiding corrodes.
- Less commonCross-threaded connectionUsually from a previous repair not done carefully.
What to do
- Turn off the shutoff valve for that line before doing anything else.
- Dry the area completely, then turn the water back on briefly to spot exactly where the leak is.
- If it's at a connection nut, try tightening it a quarter turn with an adjustable wrench, not overtightening.
- If it still leaks, turn off water again and disconnect that end to inspect the washer inside.
- Replace the washer or, if the line itself looks cracked or corroded, replace the entire supply line.
- Reconnect firmly by hand, then snug with a wrench, checking the connection is straight and not cross-threaded.
- Turn the water on slowly and check the connection closely for a few minutes.
Tools and parts
- Adjustable wrench
Braided supply lineSearch: “braided faucet supply line 3/8 inch”
When to call a pro
Call a plumber if the shutoff valve itself is leaking or won't fully close, since that needs to be resolved before the line can be safely worked on.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.