Inspection Tip: Don’t be a Drip, Get Your A/C Drain Fixed

Share News:

Every week, the detail-oriented folks at Green Scene Home Inspections will give readers an education in inspection. Want to see what they see? Tune in for “Upon Closer Inspection.”

After you’ve done several thousand home inspections, a few common themes emerge. As a homeowner, or a Realtor working with homeowners, these commonalities are good to be aware of, so you can take care of your home while you own it, and look for potential problems when you’re buying a new one. 

This week we’re looking at a very common problem in North Texas homes: clogged air conditioner drains.

Primary Condensate Line

First a quick primer on air conditioner function. An air conditioner draws in warm air and pushes out cool air, and in the process, it pulls moisture, or condensation from the air. That moisture accumulates and is drained from the A/C evaporator through a line of plumbing called the primary condensate line (pictured above).

The primary condensate line runs from the evaporator to a plumbing “trap” in the house, usually in a bathroom sink.

Over time dust and other particles in the air collect in the condensate line, which becomes an excellent environment for mold or other organic growth and this can clog the line. When the primary condensate line is clogged, the water drips into the pan under the air conditioning unit, which drains through another plumbing line — the secondary condensate line — to the exterior of the house.

Here’s an Inspector looking at a clogged primary condensate line:

How in the world am I supposed to know when my primary condensate line is clogged, you may ask?

Two things: 1) get your AC serviced; 2) the secondary condensate line is often located in a spot where you would notice that it’s dripping like in this photo, it’s outside the kitchen window.

Secondary Condensate Drain Line

Sometimes the secondary drain line comes out high up on the exterior wall, like in the next video, and you see water stains running down the siding or brick exterior. Rather than identifying the real culprit, it seems people are just extending the PVC pipe down the wall so the leaking water doesn’t stain the house.

So if you own a house in North Texas with an air conditioner, go ahead and locate that secondary condensate drain line on the outside of your house, and check it now and then to see if it’s dripping. Because if you let it go long enough, the secondary line could eventually get clogged, and now the excess water is leaking into your attic and down through the ceiling.

mm Contributor welcomes articles and op-eds from our readers and brand partners. Think you have a great story to tell? Send us a note at

Reader Interactions


  1. Andrew says

    In some condos the secondary condensate line may drain into a shower or bathtub. I know that’s the case for my Oak Lawn condo.

Leave a Reply

Your email address will not be published. Required fields are marked *