Why Does My Air Conditioning Drain Line Back Up?

There are a few reasons why your drain line on your air conditioning can back up.

Extreme Use

The main reason is due to extreme use. Your system runs approximately 8-12 hours per day depending on the time of year. In our southwest Florida climate, all that run time creates several gallons of water.


Condensation (water) is an inhibitor for algae buildup. Algae can begin to regenerate in size within 24 hours. Within 30 days the algae can double in size.


Dirt, dust, or air borne particles are the next reason. When the filters are not changed regularly (every month) dust or air borne particles will push through the filters and build up on the evaporator coil. In turn, the debris then gets washed of the coil when condensation is created from the system running and will settle in the drain line.

When you have these elements combine its allows the algae to grow by having both a water and a food source, accelerating the growth of algae.
Insects and frogs can be major cause of a clog to a drain line as well.

Underground Drain Lines

These underground drain lines are more susceptible to backups due to the installation of the line. The line connected at your indoor unit runs down under the home or condo then back up and terminates in a location in the yard. The length of this run could be as long as 50’ depending on the application. This allows water to consistently sit in the drain line throughout the year, giving algae a much better chance to grow.

Regular Maintenance

Regular maintenance is one of the keys to keeping your drain line clear. Although maintenance is preformed every six months, elements such as the ones mentioned above can cause the drain line to back up between those six months intervals. We offer an extended drain line service to help prevent expensive service calls. The service will provide additional cleanings at a reduced price.

Our extended drain line service covers you throughout the year regardless of how many trips we make; potentially saving you hundreds of dollars per year.

Call Us Today!

Please ask one of our representatives for more details if you have any questions regarding this extended service.