What you are seeing when the water level drops isn't the clog dissolving. It is the bleach, which is less viscous than standing water, seeping through the gaps in the clog. The clog is still there—you’ve just found a temporary leak. Why do people think it works? Because of the smell. A clogged drain often stinks because of anaerobic bacteria (the kind that thrives without oxygen) feeding on the gunk. Bleach annihilates those bacteria instantly. The sulfurous, rotten-egg odor vanishes.
If you have already tried a chemical drain cleaner (like Drano or Liquid-Plumr) and then decide to "boost" it with bleach, you are creating a potential deadly gas. Mixing bleach with acids (found in many "professional strength" drain openers) releases . Mixing bleach with ammonia (found in some all-purpose cleaners) releases chloramine gas . can bleach unclog drain
But a clean-smelling drain is not an unclogged drain. You have simply sterilized a blockage. Now, instead of a living, decomposing clog, you have a sterile, solid plug of hair and soap. And you may have made the problem worse. This is where the "household hack" becomes a plumbing nightmare. What you are seeing when the water level