Vinegar Vs. Bleach for Cleaning an AC Drain

by Andrew Leahey
    Window units drain condensation from the bottom of the unit's case.

    Window units drain condensation from the bottom of the unit's case.

    Air conditioners, whether they are window or central units, dehumidify the air as a byproduct of their cooling method. As they dehumidify, they remove moisture from the air and drain it through a condensate drain. Over time, this drain can become clogged with dirt and debris and needs to be cleaned. There are various ways to clean out an air conditioner condensate drain, and two popular methods are pouring white vinegar or bleach down the line to clear clogs.

    Bleach and Window Units

    Using bleach to clear clogs in the condensation drain on window-mounted air conditioners can potentially cause damage. Window units drain their condensation from the bottom of the case, which is just outside your window. Pouring bleach in to a condensation drain on a unit above decorative plants or your lawn will kill anything it pours on. Additionally, bleach can damage the vinyl siding or shingles on your house as it drains from the unit.


    Bleach and vinegar both have characteristic odors. They are not the most pleasant chemicals to smell, and you will need to wash out your drain with plain water a few times to remove the odor. Bleach vapor can actually be harmful if it is inhaled, whereas vinegar is more a nuisance than a danger. Vinegar is typically easier to rinse out of a drain line after you are done cleaning.

    Drain Line Material

    During the colder months, bleach should not be used for drain lines that are made of PVC or ABS plastic. Chlorine bleach can quickly eat away at not only the line but the glue and cement joining the line to the fittings and the condensation pan. If your drain line is PVC, stick to white distilled vinegar for clearing clogs and debris, particularly during winter.

    Preventative Maintenance

    Mold, mildew and algae will grow in your air conditioner condensation drain year-round. Using bleach during the summer months is safe as long as the unit is operating because the constant flow of condensation will wash out any bleach residue. Pouring bleach into the drain when the unit is not operating can leave residual bleach, which will damage the drain pan and line. Using vinegar for preventative maintenance throughout the year will keep your drain clean and clear and will not damage your line.

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