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4 Causes Why Humidifier Drain Line Is Clogged

In a Hot summer, you are enjoying your low room temperature because of your AC. But suddenly you realize that it has stopped working. Because the humidity drain line is clogged.

Why is your humidity drain line clogged? 

There can be many causes behind the drain line being clogged.  The first cause can be water stuck on the drain line. Then insertion of the drain line being blocked can cause this issue. The valve being reversed or opened can be the reason behind blockage too. Dirt and debris are also responsible for the problem.

The above information can not be enough for you to understand. So we would suggest that you take this journey with us. Without further ado, let’s get that drain line fixed.

What Does Your AC Humidifier Drain Line Do?

You certainly know how humid it can get in summer. This further adds to the discomfort of being outside. 

But your AC comes to the rescue. The air conditioner eliminates some of the humidity from the air and lets you experience the comfort that your money got you.

The humidifier drain line attached to your AC unit is very crucial. Any issues with this line will affect the performance of your whole system. That’s why keeping the humidifier or condensate drain line clean is a must.

Freshwater circulates through the system in a flow-through humidifier. It then drains the used water out using the humidifier drain line.

Furthermore, your humidity line is in charge of removing condensation from the evaporator coil. Plus it has another task. It empties the water from the air handler to the outside of your home.

This is why the humidifier drain line being in the perfect shape is pretty important.

4 Reasons Of Humidifier Clogging And What to Do About It

Humidifier drain lines clogging are quite common in households. Clogging can occur due to various reasons. But mainly it happens because the humidifier drain may be too old. Or you haven’t looked after it properly.

Nonetheless, there are four reasons why your humidifier drain is blocked. They are-

Reason 1: Water Stuck In The Drain Line

Sometimes water might get stuck in the drain line. This way the water doesn’t reach the sewerage line. 

There’s a high possibility of such an incident to take place if your drain line is not sloped properly. Just how shower drain being lower than the tiles causes standing water. 

If your humidifier drain line isn’t sloped, the water won’t flow continuously. As a result, it will get stuck.


Flush the humidifier drain line with water. But do it after removing any upward or downward slopes.

If needed, the drain line should be replaced. For that, ask a professional.

Reason 2: Insertion of A Scale Control Is Blocked

Scale control is also known as a water-panel evaporator. A clog in here might cause residue to build up. 

That residue later can block the drain and create pressure. This will ultimately end up creating a leak as well.


Replace the water panel evaporator or clean the inserter. You should remove the water supply tube before you start replacing the insert or cleaning the area. 

This fix also calls for an expert. Don’t try to do it yourself. 

Reason 3: Reversal of A Valve

On the valve, look for an arrow indicating the direction of water flow. By this, you have to follow the water flow. 

If you noticed that valve is in the wrong direction. Then it will build up residue and clog the drain line. 


You have to check the valve if any type of residue is stuck there. And also check the water flows through the valve. 

Make sure it’s in the correct direction. Otherwise, it would be problematic. Just how taping Teflon on sprinkler heads in the wrong way is troublesome. 

If it’s in the wrong direction, you have to try to fix it. 

You can fix it by providing water pressure or air pressure to the right of the valve. There can be other types of solutions for valves as well. But for better results, change the valve with the help of a professional.

There are many types of valves available. But we have made it easier for you by recommending top quality ones-

Product 1
Product 2

You can select any of them if you have to change your valve. 

Reason 4: Dirt and Debris

Dirt always creates problems in our household. Even our shower tiles get into a horrible situation because of dirt. As a result, you have to clean the tiles without scrubbing them. This is quite hard.

Just like that, a piece of debris or dirt can be caught between the plunger of the valve and the valve opening. This can cause issues for you by hampering the proper sealing of the valve. This ultimately blocks the humidifier drain line.

Plus if you don’t fix this soon, a leak might take place. 


Turn off the water supply by closing the valve. Turn off the power and remove the valve. 

Clean the valve now. You can clean it by pouring pressured water through it or blowing air through it.


Question: Is it better to use bleach or vinegar for the AC drain line?

Answer: Your humidity drain line contains copper tubing. The bleach can be harmful to your AC system because it will react with copper. Considering that, we would suggest that you use vinegar instead of a bleach solution. Vinegar is less likely to cause any issues to your system. Bleach spills can also damage your clothes and carpets. Whereas vinegar spills will leave an intense odor only.

Question: Should there be water in the AC drain line?

Answer: The condensate line should drain to the outside. And you should see plenty of water dripping from it during humid weather. Your humidity drain line is clogged if there is standing water in the drain pan.

Question: How much does it cost to unclog an air conditioner drain line?

Answer: The cost of flushing or repairing the line can range from $75 to $250. If the evaporator coil needs to be replaced. Then the cost ranges from $400 to $950.


We have come to the end. We have provided all the main causes for clogging in your humidifier drain line. And the solutions are also very effective and easy to apply.

Good Luck!