Clean Your Air Conditioner Drain Before it Leaks!

Air Conditioning Units produce one natural by product, Water! The method that this water is produced is just like  the water that forms on the outside of a glass with ice in it. The warmer air from your home, meets the colder surface of the evaporator coil and naturally, condensation occurs. The bad part happens when you find the air conditioner drain line clogged and a water leak on the floor!

The water that comes from your AC Unit, runs down the sides of the coil and collects inside the condensate pan, eventually reaching the condensate drain and flowing off to the drain method your installer chose. When the condensation drain becomes gummed up or plugged, that same innocent water can back up and leak, and can literally ruin your life!

Cleaning Your AC Condensate Pan and Drain Line

Face it, if you are not going to have a service company come out and service your air conditioner every season, you are going to need to do a few things on your own. Fortunately, you can do this before an AC Water Leak happens! One method of maintaining a clean condensate line, is to use ac condensate pan tablets, like tablets or another anti fungal buildup method.

According to the Tampa Handyman, one method he uses is to just grab his wet/dry vacuum, and use it to draw all the build up from your drain line, from the outside of the home, where it exits! While this will work for some, there are a few other methods to clean your AC Condensate Drain as well.

Gravity or Pumped AC Condensate Drains

In almost every instance, you will have either:

condensate-drainGravity Condensate Drain, where the water flows from your evaporator coil drain pan, directly into a small PVC drain line, and either into a drain system, in or outside your home.

As you can see in the top picture, the installer of this condensate line took the time to install a few extra pieces of the PVC drain, to facilitate the cleaning of the drain lines. Yours may or may not have these caps in place, but if you end up having to cut into the piping system to clean it,  (common on older systems) you can rebuild it with the cleanouts in place! All pieces for the new drain can be picked up at a hardware store, for less than $10, or by clicking the links below.

condensate-pumpCondensate Pump Drain System, where the water from your coil pan is piped into a small condensate pump, that automatically turns itself on and off as the water fills the collection tray.

In most cases, the PVC piping or clear plastic condensate hose, will fit directly into a hole on the top of the condensate pump, filling the reservoir. A second hose is then connected, to channel the water outside the home or into a drain system. Condensate pump systems are most commonly used in areas below the level of the homes drain.

Air Conditioner Condensate Pumps

Regardless of which system your AC system uses, almost all blockages occur in the small bend, called a trap. The trap system always holds a small amount of water, that is there to keep fumes and other objects from backing in to the system. Over time, gum builds up… the trap becomes clogged and you have a plugged ac line!

Cleaning Your AC Condensate Drain

The most common method of cleaning, is to gain access to your drain line… whether that is within a cleanout or from inside the evaporator coil drain pan, and simply flush the line with either compressed air or a water hose, forcing everything from the inside to outside. (Never flush water from outside the home, to the inside of the unit, a mess will occur!)

If you don't have access to an open end of the drain from inside, you may need to disconnect or cut the drain line to perform the cleaning.

This should be done at least once every year and more often in areas where you use air conditioning more than 6 months of the year! Doing so will prevent the AC drain from leaking water into the home!


27 Responses to “Clean Your Air Conditioner Drain Before it Leaks!”
  1. Mike Keiley says:

    I have a problem with condensate overflow. Drain line is clear, but condensate is leaking into the bottom of the unit, dripping into the overflow pan, and saturating the thermal blanket on the inside bottom of the unit, as well as the adjacent ducting.

    Coils are not icing, and unit is cooling the house well, even though we’re in South Florida and temps and humidity are high.

    Is likely cause perforation of the catch tray which funnels condensate from coils to the drain line?
    Any DIY fixes, like :radiator stop-leak:?

  2. Mark says:

    @ Mike –

    Thanks for asking the question.

    It almost sounds as if the coil drain pan may be cracked, or be leaking where the PC connects to one of the fittings.

    If the unit is a horizontal flow (lying on its side) you will see a full size pan on the bottom side of the evap coil. Up or downflow units have a collar type pans, that only circle the edges of the lower side of the coil, allowing the air to flow through the center, or around the edges.

    One way or another, you are going to have to open the sides of the air handler or coil housing and get your eyes on the pan to see where its leaking from. If its just a small crack, you can probably get some silicone and do a quick fix on it to get through another season. You WILL have to shut off the unit for several hours while you do it and make sure it has time to fully dry before turning it back on.


  3. Jill says:

    we had water start puddling in the pan of our heater downstairs. Turned out to be a bad condensate pump. my husband was shocked at just how easy it was to replace – we ordered one, it was delivered in 2 days, and we simply unplugged the brokwen pump and plugged the new one in! 5 minutes later… done!

    Thank you for the GREAT tips on this! ~ Jill

  4. Mark says:

    @ Stuart –

    Looks like an interesting and great product for sure! Thanks for the tip!

  5. stuart says:

    I am an HVAC contractor for over 25 years and the mighty pump is one of the best products that has come along. It allows me to clear drain lines without going in the home and opening the drain or trying to use a wet-vac that doesn’t have anywhere near the power this pump has and this pump does not require electric. It’s great.

  6. Jimmie says:


    We found a small water stain on our ceiling last night and discovered an overfull drain pan! The water float switch on the side shut the air conditioner off in time to prevent serious damage!


  7. Air conditioning Leakage is one of the most common problems, and it’s sad to know that owners don’t have that good ideas on how to handle such problem. And so regular check up and maintenance should be done to prevent further complications.

  8. Jim M says:

    Horizontal HVAC unit leaking water thru ceiling. Used wet vac and cleaned pvc lines but it is leaking again. Question-if the pvc lines do no have enough down hill slope could that be causing the problem ? Unit is only two years old. Got no gunk out of the lines. Is this an improper installation issue ?

  9. Mark says:

    @ Jim M –

    Have you climbed up to find where the water is leaking from? Is it leaking from the PVC pipe, or in the coil housing itself? Anyhow – FIND the exact location of the leak first. Then deal with cleaning it up!

    Also – vacuuming the drain lines out is only half of it. It may help to get a small air or water pump, and blow them out. (air mattress pumps are great for blowing OUT the lines)

    As far as it being an install issue… a drain line needs to be thoroughly flushed/cleaned at least once a year.

  10. Jim F says:

    Because we had a lot of problems with a previous AC system leaking condensate into the overflow pan I now put a water alarm in it and the water heater pan. If even a small amount of water leaks into these backup pans the alarm alerts me immediately. Battery operated water alarms are cheap insurance. I change the batteries when I change the smoke alarm batteries.

  11. Mark says:


    Great idea! Thanks for the input. I think that many people would be well served to consider your option. I know that I had an issue last summer with my drain being clogged and it caused enough of a headache to think that your solution would be a wise one for my AC drain.

  12. Doug says:

    I have a Goodman vertical air handler in my basement. It has the plastic tray. The 3/4″ knockout fitting is about 1/4″ from the bottom of the tray. With the male adapter and drain line added, the water level remains about 3/8″ deep in the tray. Is there a way to drain all of the water during operation? Is Goodman that cheap as to not make a better design?

  13. Mark says:


    I will remain impartial as to your comment pertaining to Goodman being too cheap, but I believe you are right that you cannot without taking apart the unit get to that little bit of water that sits in the tray.

  14. Carla says:

    my ac is leaking in my house. my husband is outta town so its up to me to take care of this. i have no clue about any of it! 🙂 ive read that i need to check the drain pan, except i dont know where the drain pan is… is it located inside @ my furnace or is it located outside by the actual unit itsself? i know theres a drain out there beside the unit that a lil bit of water comes out but i think it may be clogged. i saw a previous comment about using a wet/dry vac to suck the clog out of that hose. im getting ready to try that, but in the meantime is there anything else i need to do ? or can u tell me where to locate this condensate drain pan???

  15. Mark says:

    The drain pan is just above where the furnace is in most installations. You likely have some sheet metal there and a hose that is supposed to drain the water that drips from the A coil. I would check to make sure that the hose is clear (usually it is, but check anyway) and more importantly check the fitting where it comes out of the sheet metal. This is nearly always the culprit, and just happened to me last year. Use a shop vac or I used a small piece of wire to probe in there. It cleared it up quickly for me and solved the problem.

    That said, it could be many things. Check that first and let us know if it solved the problem.

  16. stanley says:

    i have a problem? i notice that my drain pan inside my unit was over flowing. so i did the drain line check and it was clogged up. i cleared the clog, tested to make sure water was going outside all that work fine. I am still getting leakage on the bottom of the unit and it is causing damage to my floor. what can be the problem now?

  17. Staci says:

    Our overflow line is leaking in the garage. My husband says the drain pan is dry. Any suggestions. We tried the bleach water mixture flush and that helped for a couple days. But it started up again.

  18. jillian says:

    mc a/c unit in the broiler room is leaking out of a small hole at the bottom of the unit. the water is running down the side of the furnace and onto the floor, but it’s not a lot. in addition to that, the unit is blowing but the air is warm. on the outside of the house, the part that connects the hose to the big unit is not cold as i was told it should be. what do you think the issue is? a service man came out and said that the system was holding the refrigerant just fine. it was ok for a few hours and now i’m back to burning up.

  19. TJH says:


  20. Mark says:

    It could be that the pan itself has a hole in it from rust or similar. That is somewhat common over time. How old is the unit?

  21. Mark says:

    Is the line itself leaking? Any noticeable cracks or holes?

  22. Mark says:


    It sounds to me like maybe you have a frozen line. The usual cause of this is low air flow. First and foremost I would see if your furnace filter is clogged. When was the last time you changed it? We suggest monthly, and in a pinch quarterly. Also, did you make sure that the outdoor unit has no obstructions and is not covered with debris?

  23. Jagadeesh says:

    My pan underneath the a/c unit in my attic was full of water when i noticed the water in my bedroom ceiling and my firealarm went off due to water getting into it…i switched off the a/c for now. i tried using shop vac on the outside line to try and remove any clogs but i didnt have any luck – nothing came out…i then crawled into the attic with my shop vac and removed the water from the pan directly so that there is no more water damage…should i try bleach or something else to blow the clog away? if so, how? please help…too hot to live without a/c…

  24. mark keeton says:

    Last night, I noticed water fell through my utility room’s ventilator. After inspecting the ac in the attic, I noticed the drip pan to the air handler bent away from the pvc pipe and dumped 2 or 3 gallons of water on top of the attic floor and a little into the walls. From what I can tell the pan was unlevel and/or the condensation built up from the last few days enough to cause it to dump. Either way after reading everyones messages on this thread, my problem is not uncommon but I am not for sure if I have further problems. I propped up the pan a little more so that the flow is aiming toward the pvc outflow. Is there anything else I need to do or check? I don’t see blockage in the pvc pipe so I am guessing the amount of water caused the overflow on the wrong side of the pan. I just want to make sure no pump or anything else is broken. I have never seen this much water before but we are experiencing almost 60 days of 100 degree heat here in Texas.
    Thaks for any assistance!

  25. Mark says:


    AC units are designed to last 12-20 years in our experience. I’m not saying it is the only option, but replacing it definitely in the cards here. Fixing the pan itself likely would require a lot of labor from the HVAC tech you choose and that alone is going to set you back a few hundred at least. Water in your home unfortunately can create many problems so I would make sure you do something to ensure the problem is fixed.

  26. Kat says:

    My a/c isn’t leaking, but it smelled like dirty feet and wet paint when we turned it on for the first time this season. Since it isn’t clogged or leaking, I’m thinking of starting first with just pouring some bleach down the drain without trying to blow it out (b/c that’s outside my skill set). What do you think? If I end up having to get the coil cleaned, will I need to take out a home loan?


Check out what others are saying about this post...

Speak Your Mind

Tell us what you're thinking...
and oh, if you want a pic to show with your comment, go get a gravatar!

WebHVAC Terms of Use - Some of the brands and products seen on this website are delivered through a relationship with outside suppliers like QualitySmith, Service Magic, Amazon, eBay, Google, and others. We may or may not be compensated for purchased you make as a result of our recommendation. This will NEVER affect our opinion of a product or service! In addition, some of the video and news is provided by Google services, Youtube video, Yahoo news, and several others. We will try to help you make the best heating and air conditioning decision whether you are using wholesale HVAC or going through a dealer.