I emptied a whole bottle of bleach into my sink just to be sure: when the flies came back three days later, I understood what was coating my pipes
You emptied bleach down your drain and watched the flies disappear—only to see them return three days later. The real culprit isn’t what you think. Drain flies hide in a protective biofilm layer that bleach can’t penetrate, and understanding this one fact changes everything about how you actually solve the problem.
