Air conditioning leaking indoors: what to do

Stop the appliance before a small drip becomes damage to your home.

The answer in 2 lines. Air conditioning removes moisture from the air, producing condensate that needs a working collection and drainage arrangement. Water dripping into the room can involve the drain, collection tray, pump or icing, but the drip alone cannot establish the cause. Stop the appliance, keep people away from wet electrics and protect nearby possessions where safe. Leave internal drainage repairs to an engineer. If you rent, report the leak promptly in writing.

The first steps

Stop cooling: use the normal controls only if they are dry and safe to touch. Before any user maintenance, isolate the supply as the instructions require.
Protect the room: move possessions away from the drip and use towels or a container where there is no electrical hazard.
Record the evidence: photograph the leak, any visible ice and the display. Note whether the water appeared during operation or after shutdown.

Stop: danger

Water near sockets, cables or the consumer unit: keep away. Switch off the affected supply only from a dry, safely accessible position. Do not touch wet switches or plugs.
Wet electrical equipment: keep it out of use until a qualified professional has checked it. Drying the outside does not establish that it is safe.
Smoke or fire: get out, stay out and call 999. Do not use water on an electrical fire.

Understand where the water should go

A fixed indoor unit normally collects condensation and sends it through a drain, sometimes with a pump. A portable appliance may use a tank, a drain connection or another arrangement described in its instructions. Check which type you have before attempting to empty anything.

Do not assume water on the wall must be refrigerant, or that a dry-looking drain outlet proves a blockage. The amount and route of condensate depend on the installation and operating conditions. The important change is water escaping somewhere it should not.

Possible causes to discuss with the engineer

Water beneath a fixed indoor unit: ask for the condensate tray, drain route and connections to be checked.
A system using a condensate pump: the pump, controls or discharge pipe may need assessment.
Ice followed by water: record the ice without removing covers. Airflow and refrigeration faults are possibilities, not a diagnosis.
A leak after installation or servicing: contact the installer or service provider and show when and where it started.

Ask for the cause to be recorded in the repair report. Clearing water from the floor without addressing its source leaves the problem unresolved.

What not to do

Running the appliance unattended with a bowl underneath it.
Pushing wire into the drain, using drain chemicals or disconnecting concealed pipework.
Tilting a wall-mounted unit, opening its casing or chipping ice away.
Switching wet electrical equipment back on simply because it appears dry.

What you can check safely

Read the model's instructions for user-accessible filters and any tank-full message. Clean only filters intended for user cleaning, using the specified method, and refit them only when ready according to the instructions. If access requires tools, awkward reaching or working beside wet electrical parts, stop.

Check a portable unit's tank and drain only by its documented procedure. For a fixed installation, leave changes to pipe slope, pumps, trays and concealed drains to a competent engineer. If refrigerant work is proposed, use GOV.UK's certification guidance to check what evidence to request from the contractor.

Report damage and agree the repair

If you rent, send the landlord photographs and explain whether water has reached electrical fittings, walls or another flat. Check the tenancy agreement before arranging chargeable work. For the general repair duties and escalation route, read GOV.UK's repairs guidance. Responsibility for cooling equipment needs checking against the circumstances; it should not be assumed from the drip alone.

Tell your home insurer about damage in accordance with your policy. Keep photographs and receipts, and ask before discarding damaged belongings. Housing rules differ in Wales, Scotland and Northern Ireland.

Good to know

Condensate draining at its intended outlet can be normal; water escaping into the room needs attention.
For wet appliances, the public guidance from London City Hall advises a professional check before reuse. Read its flooding precautions for the electrical safety steps.
There is no safe generic instruction to restart a leaking system: follow model-specific advice and the engineer's findings.

Illustrative example: in Leicester, Priya notices water beneath a wall-mounted unit. She stops it, moves furniture away and photographs the damp wall. Because the drain is concealed, she leaves it alone and contacts her landlord. The engineer investigates the condensate route and explains the repair before the appliance returns to use.

A made-up story, for illustration.

Bobby

Sources, verification, confidence

Verified on 5 November 2026, for England. Confidence: high for electrical precautions and F-gas certification requirements; medium for possible causes, which require inspection. The official condensate reference concerns building design rather than a domestic troubleshooting procedure. No universal maintenance interval or insurance deadline is asserted.