Troubleshooting Your New Sink: What to Do If It's Leaking

Troubleshooting Your New Sink: What to Do If It's Leaking

You've just finished your DIY sink installation, and everything looks perfect—until you spot that unwelcome drip. Leaks in a new installation are almost always due to a simple seal failure or a loose nut, not a faulty product. Before you panic and call a professional, follow this focused troubleshooting process.

Step 1: The Faucet Connection Check

Leaks often start with the water supply lines. Turn off the main water supply and check the following:

• Supply Line to Faucet: Reach up under the sink and ensure the nuts connecting the braided supply lines to the faucet tailpieces are tightly secured (hand-tighten, then give a quarter turn with a wrench).
• Supply Line to Angle Stop: Check the connection at the wall (the shut-off valve). If this is dripping, the nut or washer may not be fully seated.

Fix: Tighten the nuts slightly, dry the area, and turn the water back on to re-test.

Step 2: The Disposal/Drain Flange Check

The failure of the seal around the drain opening is common because the plumber's putty or silicone wasn't perfectly sealed.

• Drain Flange: For a non-disposal drain, ensure the large locknut under the sink is tight. For a disposal, make sure the mounting ring is seated firmly and the drain locknut is tightened against the sink material.
• Plumber's Putty Failure: If the leak is between the flange and the sink, you'll need to disassemble the drain, clean off the old putty/silicone, apply a fresh bead, and re-tighten.

Fix: Disassemble, apply fresh plumber's putty to the flange, re-seat, and re-tighten the locknut.

Step 3: The P-Trap and Pipe Joint Check

The most frequent leak source after a DIY installation is the P-trap assembly.

• Slip Joint Leaks: Leaks here usually come from the slip joint nuts that connect the P-trap and the tailpiece.
• Washer Seating: When you tighten these plastic nuts, you must ensure the tapered washer inside is sitting perfectly flat against the pipe.

Fix: Loosen the slip joint nut, ensure the washer is positioned correctly, and re-tighten. Always start tightening by hand, then use a wrench only to snug the nut a quarter turn past hand-tight. Over-tightening can crack the plastic.

Remember, always have towels ready, and dry the area completely after each attempted fix to ensure you know where the new drip is coming from.

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