Said It Here

How to get off a sink locknut put on upside down

Standard basin wrenches cannot grip the reversed notches of a sink locknut installed upside down, making it nearly impossible to loosen. This prevents homeowners from removing the nut to fix a loose seal or correct the installation.

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

  1. 1
    buying specialized basin wrench tools
  2. 2
    Holding the bottom nut with a wrench while using another wrench to turn the top insert counterclockwise
  3. 3
    Using a longer wrench for more leverage

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.

r/Plumbing2 people · September 2026

Today, I realized I accident put on the locknut underneath the sink upside down, meaning the seal isn’t as tight as it should be. Now here’s my real problem. I can’t get it loose to flip it right side up. I went and bought one of those tools that’s specifically for loosing and tightening it, but because it’s upside down, I can’t get the tool around the notches.source ↗

wbertolone · r/Plumbing · 2 upvotes

I’m struggling to get the old one off.source ↗

I understand that the hoses need to be disconnected from the piping, but I can’t figure out how to loosen the nuts.source ↗

seedofbilly · r/Plumbing · 1 upvotes

Where this came up

People with this problem also raised