Why Do Heat Pumps Leak Water? What To Look For & How to Fix Issues

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Frigidaire heat pumpphoto: Frigidaire

It's a great feeling to be able to reach for your heat pump remote, click it on, and relax when you want to stay comfortable in your home, even on the hottest day.

But hang on! – There's water seeping out of your heat pump?

Is that serious, and what should you do?

Read on for advice about water leaks in heat pumps, why they leak, and what you should do when it happens.

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Why do heat pumps leak water?

That's right; heat pumps naturally expel water as part of their function.

But you should never be aware of the normal draining of condensation, which is naturally produced by all air conditioners or heat pumps. If there is a puddle of water or drips coming from your unit, then there's an issue.

What are the main types of the heat pumps?

There are six types of air conditioning or heat pumps, and they all share the same issues when it comes to leaking water.

These are:

  • Central systems
  • Ductless type
  • Window type
  • Portable type
  • Hybrid type
  • Geothermal systems

Conditioning the air for your home will probably be handled by one of these systems. They all drain off condensation from the air conditioning process. So why do all of them leak water?

Central heat pump system leak water

Your central heat pump unit has an evaporator coil that cools the air as it passes across to cool your home. The condensation that forms drains via a pipe into a drain pan, which empties to the outside.

If your central unit is in a basement, you will have a drain pump to remove the water.

There are a few things to check.

The drain tray can block with debris, causing an overflow and a leak. Clean the tray, remove the debris, then the water should run off freely. Debris may also go down the drain pipe, so flush it through with clean water and some household bleach.

If you have a drain pump, check it is working. Clean the filters and flush them with clean water to ensure they're clear.

If your pump has failed, replace or repair it to prevent further risks.

In some cases, the drain tray is corroded and may be punctured. Fit a replacement, or apply a temporary fix with waterproof tape until you can get a new one.

If your air filter is clogged, the fan has failed, or is damaged; these can lead to water leaks. These reduce the airflow across the evaporator coil, causing it to freeze. When the ice melts, it overflows the drain tray.

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Do portable heat pumps leak water?

Perhaps portable heat pumps and air conditioners are the most likely to leak water because they are mobile and need to be emptied. They are not normally connected to an external drain. Instead, they have a water reservoir that needs emptying.

If there is a leak, the container may simply have been bumped when full and spilled; it could be damaged, or the drain line disconnected, split, or blocked. Most units have a float valve, which will shut the unit off when the tank is full.

Some modern units expel condensate along with hot air via the exhaust pipe into the atmosphere; no draining is required, so there are no leaks.

Yes, window-type heat pumps also leak water!

One of the main reasons window heat pumps leak is the incorrect installation of the unit and drain tray. They need to sit at a specific angle to work correctly, so if it's leaking, it may be at the wrong angle. If the air filter is clogged, the fan is stopped or damaged; it will reduce the airflow, which will freeze the evaporator coil.

This will cause excessive water as the ice melts. Check the drain pipe hasn't been detached or split, and if it's intact, look for possible blockages or twists in the pipe. Ensure your drain tray is clear of debris and your drain pump is working.

Make sure the seals around your window unit are tight. If not, hot air from outside can enter your unit where the air is cold. The hot air in the moisture will condense, causing an excess of water inside the unit and a leak.

My split heat pump is leaking water into my home!

Split heat pumps leak water naturally. But where they leak is the issue. If the condensate follows the correct built-in drain path, then you will never see any puddles or drips, but if the drain line gets clogged, it will back up and flood your home. It will overflow down your walls.

Drain connections are worth checking regularly. Dirty, clogged filters and damaged or failed fans will slow the airflow causing icing on the coil, which, when it melts, can overwhelm the drain pan and leak.

Poor installation can cause water to build up and start dripping into your home, causing damage to walls, furnishings, floors, or carpets.

Is it a refrigerant or water leak? How do I know?

A heat pump refrigerant leak is a more serious issue. It is sealed within the unit and shouldn't leak unless there is corrosion, physical damage, or old age.

With a refrigerant leak, you may be aware of a hissing noise coming from the unit. The leak may not be clearly visible. Remember, too; a refrigerant leak will make the system work harder due to the loss of pressure, which will increase power bills.

If you experience reduced airflow or a pool of water around the unit, you could have a refrigerant leak, and the evaporator coil will freeze.

You will see ice on the coil and the copper lines. The ice melts, and it leaks water.

If you suspect a refrigerant leak, close your system down immediately and call a qualified HVAC technician to check your system. See the EPA Guide (pdf).

If you continue to run your system with a leak, it could cause severe damage.

The most frequently used refrigerant today is R-410A, which is non-toxic and non-flammable with no odor so that you won't smell it, unlike the older gasses.

The main causes of water leaks, how to prevent & fix them

Rarely poor installation is the cause of water leaks in your system.

Physical damage happens, but the main reasons are dirty air filters blocking the airflow through your system are the leading causes. Clean your filters regularly, and check for fan damage that will compromise the airflow.

An HVAC annual professional check will help catch any issues early and prevent them from becoming more serious.

When you clean the filter, check your drain line is clear and that the drip tray is free of gunge and corrosion. If you have a condensate pump, clean the filter and ensure it's running smoothly.

Have a P-Trap fitted to your drain line to prevent backup if there's a blockage. It will stop water from leaking inside your home. If you do these few simple things, your system will run sweetly.

Is using my heat pump safe when water is leaking?

It is not advisable to run your unit with an apparent water leak. Shut it down and find the source, fix it, and you will be good to go again. The main thing to consider is the source of the leak and the volume of water leaking, especially inside your home. Any leaking water can potentially encourage mold, which is an unwelcome visitor. If the culprit is a blocked condensate drain, then unblock the drain and restart the unit. It shouldn't take very long.

If your heat pump is leaking, it may be because it’s freezing up and it's defrosting. Allow the unit to defrost fully, collect the water that's leaking out to prevent damage, and wait until it's fully defrosted before running it again. Freezing can be caused by low airflow, lost refrigerant, or a failed, faulty, or damaged fan. Faulty thermostats can cause freezing/defrosting and subsequent water leaks.

When should I call a professional & what will it cost?

The average cost for annual AC/heat pump checks in the US is between $100 and $150. The average is around $125, which is the same as the national average for this work. The minimum cost is about $70, and the highest in the US is $195. Check out this website for costs.

Most Canadians will spend between $300 and $1000 per year on AC or heat pump maintenance. The larger your home, the higher the cost will be. Check here for more Canadian prices.

Always call a professional HVAC technician for suspected refrigerant leaks. They have the expertise and specialist equipment to carry out testing quickly.

If there is a fire, or faulty electrical wiring or components, always shut off the power and call a professional unless you are qualified and certified to do the work safely.


The old advice is still valid – have a registered HVAC technician service you heat pump annually, and it will be worth it.

Do your bit in between. Be aware of what's happening in and around your home, encourage your family to do the same, and get them to report anything odd they see, hear or smell. It could save you a disaster.

Clean your system's filters regularly and check for leaks and odd unexplained puddles of water unless you have a new puppy, of course!

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