We recently had a leak with our guest room bath toilet and it went unnoticed for 3 days. We cleaned up the water and repaired the leak. After a few more days, we noticed black discoloration on the linoleum flooring. Is this mold?
- Marcia and Harry from Chino

Marcia and Harry, yes it is quite possible you have mold under the flooring material. When a leak occurs, it is important to dry out the area within 24-36 hours, and if this is not done, mold will grow. Linoleum is a “vapor barrier” type of floor covering and does not allow air in so the leak can dry out. It is unlikely that black spots/mold would occur from a leak in a short period of time. It sounds as of there was a prior leak that was not dried properly and therefore, mold was already beginning to grow. Moisture is held captive and cannot escape and it takes approximately 1-2 weeks to find and see significant mold growth. It is critical to mitigate mold in a proper manner and to keep the mold spores contained to prevent the mold spores from becoming air borne. People who are not certified and trained should not be contracted to correct mold removal issues.