How do I find the source of a mysterious bathroom leak?
Water pooling between a vanity and a toilet can leave wood swollen and create confusion over whether the issue stems from the plumbing or the wax ring. Without clear first steps, it is difficult to determine where the water is actually coming from.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1checking connections and hoses under the sink and toilet
- 2placing paper towels and dry tissues around suspect areas to trace moisture
- 3running water and observing for drops
- 4checking stacked bathrooms and surrounding areas for moisture
- 5Opening the ceiling to investigate and let it dry
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 · October 2026
“The wood at the base of the vanity is swollen...where the heck is this leak coming from?!?!”source ↗
Character-Box4202 · r/Plumbing · 1 upvotes
“Question - if the paper towel is wet in the morning with no toilet flushing in between, would that exclude the wax ring?”source ↗
Character-Box4202 · r/Plumbing · 1 upvotes
Where this came up
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