How often should you flush your AC condensate drain line?

Skipping it eventually leads to water damage or an expensive repair.

Staying on schedule matters beyond the repair bill: a consistent maintenance record is one of the factors in a home's Roots Home Health Score, and well-kept homes typically sell faster and closer to asking price.

How to do it

As the AC cools air, it pulls moisture that drains away through a PVC line. Algae clogs that line, and a backed-up drain overflows the pan into the ceiling or floor below.

1. Turn the system off at the thermostat and breaker.
2. Find the drain line's access tee (a capped PVC pipe near the indoor unit) and the outdoor exit.
3. Pour a cup of distilled vinegar into the access port, or use a wet/dry vac at the outdoor exit to pull the clog out.
4. Confirm water runs freely, then pour a little more vinegar to slow regrowth.

Alternatives & optional extras

• A monthly vinegar pour in cooling season keeps algae from ever clogging it.
• A float switch on the drain pan shuts the system off before an overflow; worth adding if yours lacks one.

Time: 20 minutes · Typical cost: Free, or $5 for vinegar

What you'll need

• Wet/dry shop vacuum

If you skip it

A clogged condensate line backs water up into the drain pan and overflows into the ceiling, walls, or floor below the air handler.

Other air conditioner maintenance

• Schedule AC tune-up — once a year, ideally in April
• Clear 2 ft around outdoor AC unit — once a year, ideally in May
• Replace AC air filter — every 3 months

Related systems to keep on schedule

• Boiler / radiators — start with: schedule boiler service, once a year, ideally in September
• Furnace / heating system — start with: replace hvac air filter, every 3 months
• Mini-split / ductless AC — start with: clean mini-split filters, once a month
• Tankless water heater — start with: descale tankless water heater, once a year