Stain colour
Colour on drywall is a hint about the water’s path, not a chemistry report.
Green-blue marks often show up under copper lines. Brown marks often show up under old moisture. Neither colour lets you skip investigation.
By ProShield Leak Detection Inc. · Updated
Photograph colour before anyone primes.
Primer erases the only hint you had.
Do not scrape a sample into a bag as a hobby.
You can make a hole without a source.
Match the stain to a pipe run if you can see one in a closet.
A green ceiling under a copper closet is a useful sentence.
Questions people ask
Does green mean pinhole for sure?
No. It raises copper as a suspect. Confirm with a visit.
Should we test the water?
Building water chemistry is an assessment question when pinholes repeat. One stain does not require a lab kit from a hardware store.