Can I use hydrogen peroxide to clear a clogged AC drain?

Yes, you can safely use standard household three percent hydrogen peroxide to help clear and clean a clogged or slow-moving air conditioning condensate drain line. Hydrogen peroxide is an effective oxidizing agent that breaks down organic matter, destroys mold spores, eliminates stubborn algae, and kills bacteria hiding inside the PVC drain pipes without relying on toxic chemicals or harsh acids that could damage your plumbing. To use it, simply pour about one cup of straight three percent hydrogen peroxide down the T-pipe vent opening or directly into the condensate drain pan once every month or two as a preventative measure. It reacts with organic buildup to foam and lift debris away from the pipe walls. However, if the drain line is completely blocked with a solid mass of hardened sludge, pouring peroxide alone may not be enough, and you will likely need to clear the clog using a wet-dry vacuum on the outdoor drain exit.