- Most common cause
- Blocked drain dust, slime or insects
- Worst in
- Cooling and dry mode most condensation
- Professional service, single unit
- $79–$249 typical per visit
When a heat pump cools or dehumidifies, it pulls water out of the air. That water collects in a tray under the indoor coil and runs out through a small drain hose, usually to the outside wall or a gully. If anything stops it flowing, the tray overfills and water runs down the wall from under the unit. It is a nuisance rather than a danger, but left alone it will stain the wall, swell plasterboard and can lead to mould.
Why is my heat pump leaking water inside?
- A blocked condensate drain. Dust that gets past dirty filters mixes with water to form slime in the tray and hose. Insects and spiders also nest in the outside end of the hose.
- A kinked, crushed or badly sloped drain hose. The hose needs to fall all the way from the unit to where it discharges. A dip or a rise lets water sit and back up.
- Dirty filters and an iced coil. Restricted airflow can let the indoor coil get so cold it ices up in cooling mode. When it melts, more water arrives than the tray can handle.
- A unit that isn't level. If the indoor unit tilts away from the drain side, water pools at the wrong end of the tray and overflows.
- A condensate pump that has failed. Where the drain can't fall to the outside, a small pump lifts the water. If it stops, the water has nowhere to go.
What should I do right now?
What to do when a heat pump drips water indoors
- Turn it off
Stop the unit with the remote and switch it off at the isolation switch. Water and electrics don't mix, and running it makes more water.
- Protect the wall and floor
Put a towel or tray underneath, move furniture and electronics away, and wipe the wall dry so the lining doesn't soak.
- Clean the filters
Dirty filters are behind many drain blockages and iced coils. Clean them now so you don't make the same problem again. Our filter cleaning guide has the steps.
- Check the hose outside
Find where the drain hose comes out. Make sure the end isn't buried in garden, squashed, blocked with leaves or full of insects. If water starts flowing once you clear the end, that was likely the problem.
- Book a service if it drips again
Clearing the tray and the hose along its full length, checking the slope and testing any condensate pump are jobs for a technician. They are a routine part of a proper service.
Is water from the outdoor unit normal?
Yes. In heating mode, the outdoor unit collects condensation and regularly defrosts its coil, so water and sometimes steam come out of it, especially on cold mornings. That is normal and is not a leak. Keep the ground around it clear so the water can drain away, and if it pools onto a deck or path, ask for a drain to be fitted from the base of the unit.
Why does a new heat pump leak water?
On a new install, a leak usually points to the installation rather than the unit: a drain hose without enough fall, a kink where it passes through the wall, or an indoor unit that isn't level on its bracket. That is a workmanship issue, so call the installer back first. A competent install tests the drain by pouring water into the tray before the job is signed off, which our installation process guide covers.
Can I clear a heat pump drain myself?
You can clear the outside end of the hose and keep the filters clean. Opening the indoor unit to clean the tray, flushing the hose with a pump or chemicals, or adjusting the unit on its bracket is technician work. It is easy to damage the coil fins or the electronics, and spraying cleaners inside the unit is something manufacturers warn against.
A service typically costs $79–$249 per visit for a single wall or floor unit, and should include checking and clearing the condensate drain. See heat pump servicing for what else to ask for.
Frequently asked questions
Why is water dripping from my heat pump indoor unit?
Almost always because the condensate drain is blocked, kinked or not sloping away properly, so water backs up and overflows the tray. Dirty filters and an indoor unit that isn't level are the other common causes.
Is a heat pump leaking water dangerous?
It is not usually dangerous, but switch the unit off at the isolation switch, keep water away from power points and electronics, and dry the wall to prevent damage and mould.
Why does my heat pump leak only in summer?
Cooling and dry mode pull the most water out of the air, so a partly blocked drain that copes in winter overflows in summer.
Is it normal for water to come out of the outdoor unit?
Yes. In heating mode the outdoor unit produces condensation and defrost water, often with steam on cold mornings. That is normal.
My heat pump is new and leaking. What do I do?
Call the installer back. On a new install, a leak usually means the drain hose doesn't have enough fall or the unit isn't level, which is a workmanship issue for them to fix.
How much does it cost to fix a leaking heat pump?
Clearing a blocked drain is normally part of a standard service, which typically costs $79–$249 for a single unit. A failed condensate pump or a re-run drain will cost more; ask for a quote first.