Said It Here

How to tell if crusty residue on a basement pipe is a sewage leak

Crusty crystallized residue or visible cracks around basement joints often indicate active leaks from cracked sewer or drain pipes. This uncertainty prevents homeowners from knowing whether the moisture is a major sewage issue requiring immediate repair or a minor plumbing fix.

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
    Testing for moisture with a single ply of toilet paper
  2. 2
    Using sewer gas leak detectors to sniff around the joints
  3. 3
    Turning the valve back and forth
  4. 4
    Turning water off by the road to the whole house

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/Plumbing4 people · September 2026

“There is crusty crystallized residue around a few of the joints.”source ↗

Gabreality · r/Plumbing · 2 upvotes

“Zoom in on the first pic and you can see a crack that’s poo water”source ↗

Trick_Magician_5016 · r/Plumbing · 1 upvotes

“it was squirting water out where the red latch connects to the pvc.”source ↗

“Since it’s coming out of the wall on basement is this one of my main water valves?”source ↗

“Any ideas as to what water line it is. Why it would be squirting and is it easy fix”source ↗

RunLucky1008 · r/Plumbing · 1 upvotes

“What does it go to?”source ↗

Yagsirevahs · r/Plumbing · 1 upvotes

Where this came up

People with this problem also raised