About The Author: Travis Baugh is a Digital Brand Marketing Manager for Bryant, where he creates clear, helpful content to guide homeowners through heating, cooling, and indoor air quality decisions. His goal is to empower readers with the knowledge they need to choose the right comfort solutions for their home—confidently and comfortably.
Furnace Leaking Water? Here’s Why and How to Fix It
Why is my furnace leaking water? A furnace leaking water typically signals a blockage or malfunction in the condensation drainage system. Common culprits include a clogged condensate drain, a frozen discharge line, or issues with a humidifier. While high-efficiency furnaces naturally produce water, pooling on the floor requires immediate attention to prevent water damage.
What Causes a Furnace to Leak Water?
If you see water pooling around your furnace, it is likely due to a blockage or malfunction in the system's drainage components. High-efficiency furnaces create condensation during operation, and this moisture needs a clear path to exit. When that path is blocked or broken, water leaks out.
If you spot water pooling around the base of your unit, the issue usually stems from how the system manages condensation. High-efficiency furnaces create moisture as they operate, and this water needs a clear path to drain. When that path is blocked, cracked, or disconnected, leaks occur.
Here are the most frequent reasons for a furnace leak:
Clogged or Blocked Condensate Drain
This is the most common culprit. High-efficiency furnaces produce condensation while cooling air in the heat exchanger. This moisture travels through a condensate drain. If dirt, debris, or algae block this drain, water backs up and spills out.
Andrew Mackey, owner of Superior Service in Lake St Louis, Missouri, sees this as the most common reason for a furnace leaking water.
“A furnace itself would only be leaking water if it is a high-efficiency unit,” Mackey said. “In most cases, the drainage system for the condensation is clogged and needs to be serviced or replaced.”
Frozen Condensate Line
In freezing temperatures, an improperly insulated condensate line can freeze shut. This ice blockage prevents water from escaping, forcing it to back up into the furnace and leak onto the floor.
Faulty Humidifier
If your system includes a furnace humidifier, a leak might stem from a crack, loose connection, or clogged filter within the humidifier itself. This can cause water to drip onto the furnace or the surrounding area.
Cracked Heat Exchanger
A cracked heat exchanger is a serious mechanical failure. It can prevent the system from channeling moisture correctly, leading to leaks. Important: A cracked heat exchanger can also lead to dangerous carbon monoxide leaks. If you suspect this, call a professional immediately.
Improper Installation
If the furnace or its drain lines weren't installed with the correct slope or secure connections, water won't drain effectively. This often results in slow leaks that appear shortly after a new furnace installation.
Dirty Furnace Filter
A clogged furnace filter restricts airflow, causing the evaporator coil to freeze or the furnace to overheat. When the ice melts or the system struggles, it can result in excess moisture leaking out.
Faulty Condensate Pump
Many high-efficiency units use a pump to push water away from the furnace. If the pump fails or loses power, the water reservoir will overflow.
What To Do When Your Furnace Is Leaking Water
If you discover a leak, act quickly to protect your home from water damage.
- Turn Off the Furnace: Immediately switch off the unit (and the thermostat) to stop water circulation and prevent electrical shorts.
- Clean Up Water: Soak up standing water to protect your flooring and prevent mold growth.
- Check the Filter: Inspect your air filter. If it is dirty, replace it. This is a simple fix that often resolves airflow-related leaks.
- Inspect the Drain Line: Look for visible blockages or kinks in the condensate line. If it is cold outside, check if the line is frozen.
- Check the Humidifier: If equipped, ensure the humidifier isn't overflowing or leaking from a loose connection.
- Call a Professional: If the filter is clean and the drain looks clear, the issue may be internal (like a pump failure or cracked heat exchanger). Contact a local Bryant dealer to schedule a furnace service appointment.
Safety Note: While you can check filters and external lines, avoid opening the furnace cabinet to fix internal components.
Mackey cautions customers against trying to do too much furnace troubleshooting on their own.
“We recommend the homeowner to call a qualified and licensed contractor to troubleshoot a furnace,” Mackey said.
Connect with A Bryant Dealer On Furnace Leaking Water
With a trusted Bryant dealer, you can be confident that the issue of a furnace leaking water will be resolved safely and efficiently. They can diagnose why your furnace is leaking water and perform the appropriate furnace repair.
By connecting with a Bryant Dealer, you’re choosing a professional with the expertise, tools, and furnace parts needed to properly fix your furnace and ensure it operates efficiently for years to come. Schedule an appointment today.
Furnace Leaking Water FAQs
A furnace leaking water is usually not an immediate emergency, but it should be addressed quickly to prevent water damage and system failure.
Water may leak from a furnace due to a clogged condensate drain, cracked drain pan, or a malfunctioning condensate pump in high-efficiency models.
Yes, high-efficiency (condensing) furnaces normally produce water as part of the heat exchange process and drain it through a condensate line.
Turn off the system, clean up any standing water, and call an HVAC technician to diagnose and repair the source of the leak.
Yes. Turn off the system and call a professional to prevent electrical or water damage.
Minor condensation hose issues can sometimes be cleared, but most leaks require a professional HVAC technician to inspect the drain, humidifier, or heat exchanger.
It can indicate a problem with the condensate system or secondary heat exchanger and should be checked promptly.
High-efficiency furnaces naturally produce some condensation—typically a few gallons per day during heating—but pooling or dripping is not normal.
Learn More About Furnaces
- Explore furnace replacement
- Learn how much is a new furnace
- Get help with a furnace not turning on
- Find out how to fix a furnace blowing cold air
- Learn about the importance of furnace cleaning
- Understand the ins and outs of a furnace tune-up
