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uk Home & property emergencies

What to do if…
an air-conditioning or HVAC unit starts leaking water indoors

Produced and maintained by PanicStation.org Published: Last reviewed: Editorial policy UK guide

Short answer

Switch the unit off using dry, normal controls and stay away from any wet electrical fittings. Contain the dripping water only where it is safe, then contact the person responsible for maintaining the system or an air-conditioning engineer.

Do not do these things

  • Do not keep running or repeatedly restart the unit to see whether the leak stops.
  • Do not touch a wet plug, socket, switch, isolator, cable, consumer unit, or appliance control.
  • Do not remove electrical covers or open the unit casing.
  • Do not stand in water while touching electrical equipment.
  • Do not climb on unstable furniture to reach the unit or its drainage pipe.
  • Do not stand beneath a sagging, bulging, cracked, or shedding ceiling.
  • Do not puncture a bulging ceiling or pull down wet plaster.
  • Do not assume the liquid is refrigerant solely because it came from an air-conditioning unit.

What to do now

  1. Switch the air-conditioning or HVAC unit off using its remote control or another normal control that is completely dry. If the control, plug, socket, or isolator is wet, do not touch it.

  2. Keep people and pets away if water is near electrical fittings or equipment. Switch off the electricity at the consumer unit only if you can reach it safely without touching wet surfaces or entering standing water.

  3. Call 999 if there is fire, smoke, sparking, a burning smell with signs of electrical danger, or an immediate risk to life. Otherwise, arrange urgent help from a registered electrician if water has entered the consumer unit or affected fixed electrical fittings.

  4. Put a bucket or waterproof container beneath the drip if you can do so without touching the unit, wet electrics, or damaged ceiling material. Use towels to slow the spread of water, keeping them clear of plugs, sockets, extension leads, and cables.

  5. Move nearby possessions away from the wet area. Keep out of the room if the ceiling is sagging, bulging, cracking, or shedding material, and report the building damage urgently.

  6. From a safe position, take a few photographs and note whether the water appears to come from the indoor unit, pipe casing, wall, or ceiling. Do not dismantle anything to investigate further.

  7. Contact the installer, maintenance provider, building manager, or an air-conditioning engineer. Tell them the unit is off, where the water is visible, and whether it has reached electrical fittings or damaged the ceiling or wall.

  8. If you rent, report the leak promptly in writing to your landlord, letting agent, housing association, or council repairs service. Use any emergency repair contact they provide and keep a copy of your report.

  9. If switching off the unit makes the room too hot, move to a cooler room, close curtains on sun-facing windows, drink water, and use a separate fan only in a dry area. Check NHS guidance if anyone becomes unwell in the heat.

What can wait

You do not need to work out whether the cause is a blocked drain, condensate pump problem, frozen component, damaged pipe, or installation fault. Cleaning inside the unit, buying parts, redecorating, making an insurance claim, and deciding whether to replace the system can wait until the area is safe and the cause has been assessed.

Important reassurance

Water leaking from an indoor air-conditioning unit can have several causes, many involving condensation or drainage, but the cause cannot be confirmed safely from the drip alone. Switching the unit off, avoiding wet electrics, limiting the spread of water, and arranging an inspection are useful first steps.

Scope note

This guide covers immediate safety and damage-limitation steps only. Repairs to the appliance, drainage system, electrical installation, ceiling, wall, or other building fabric may require appropriately qualified specialists.

Important note

This is general information, not electrical, engineering, medical, legal, insurance, or other professional advice. Follow instructions from emergency services and the advice of the manufacturer, landlord, building manager, insurer, or qualified contractor dealing with the incident.

Additional Resources

Closely connected guides that may be useful during the same situation or its immediate aftermath.

About this guide

This guide was produced and is maintained by PanicStation.org using its published editorial process. Official and specialist sources are checked where relevant, and AI-assisted tools may be used for drafting, organisation, and consistency checks. The site operator remains responsible for publication, revision, and removal decisions.

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