What is the brown gunk in my washing machine?
There could be any number of things in your washing machine that could cause the brown gunk, but the most common culprit is detergent residue. If you're not using enough laundry detergent, it can build up and form suds, which will eventually release the built-up detergent into the water. This brown gunk can also be caused by fabric softeners, bleach, or other harsh chemicals used in your washer.