HOME » Water Leaking

Water Leaking

Air conditioning leaks can be frustrating AND MESSY! They can cause significant water damage to your home. If you detect leaking water, you should shut the system off.

Common Causes of AC Water Leakage

The following issues can cause water leaks in your central AC system:


A clogged drain line (condensate line) is the most common cause of water leakage. A drain line is a pipe leading from your indoor unit (air handler, electric furnace or gas furnace) to an exterior drain or condensate pump. Its purpose is to drain water from the system’s drain pan.

A clogged drain line can cause your system’s drain pan to overflow. Drain lines can become clogged by dirt, rust, algae and other debris.

As summer temperatures and humidity rise, the more condensation (water) your air conditioning system produces and it becomes especially important to ensure the line is clear.

You can help keep your drain line clear by checking it regularly for visible debris. During the summer, you should be able to see water draining outside or to a floor drain.

If you do not see water draining or if water is backing up, you can try to clear the drain line out yourself with a shop vac or air compressor. You will need to disconnect the line from the indoor unit in order to do this.

We also recommend using a 50/50 bleach and water solution to periodically clean the drain line. Use about a cup bleach mixed with a cup of water. You should pour this mixture down the drain line to help clear it of algae. You should always take precautions when handling bleach.

As a precautionary measure, Goff HVAC can install an emergency float switch. This device is very affordable, especially compared to the damage that can result from leaking water. An emergency float switch is designed to shut the system off automatically if it detects water backing up in the drain pan.


A disconnected drain line can leak water onto the floor or through a ceiling depending on where the indoor unit is located (closet, mechanical room, attic). A drain line can become disconnected from the indoor unit (air handler, electric furnace, gas furnace) if it is accidentally bumped. Over time, a drain line can also become loose, causing it to disconnect.


Some systems have a condensate pump. Many times, a condensate pump is used to pump water out of the home. This is especially common when the indoor unit is located in a basement or crawlspace.

A malfunctioning or dirty condensate pump can cause water leakage, flooding your attic or basement. Due to the continual presence of water, mold and mildew can grow inside the unit, causing it to clog.


  • Clogged air filter
  • Low refrigerant
  • Cracked condensate drain pan
  • Missing p-trap and/or air vent in the drain line
  • Condensate buildup in uninsulated ductwork


Follow these tips to reduce the likelihood of water leakage issues:

  • Maintenance your system regularly or contact Goff HVAC about a Preventative Maintenance program.
  • Add a secondary drain line, especially if your indoor unit is located in the attic or above another condo or apartment.
  • Add an emergency float switch installed, especially if your indoor unit is located in the attic or above another condo or apartment.
  • Add a secondary safety pan under your indoor unit to catch drain pan overflow.
  • Clean or change your air filter(s) regularly.
  • Make sure your ductwork is properly insulated.
  • Have your refrigerant levels checked regularly.
  • Ensure each drain line contains a p-trap and air vent.
  • Keep your condensate pump free from mold and mildew by flushing it with a 50/50 bleach and water solution.
Call Goff HVAC Now!
Scroll to Top