Why an AC makes water in the first place
Cooling air also dries it. As warm, humid room air passes over the cold indoor coil, moisture condenses on the metal, drips into a tray under the coil and runs outside or to a waste pipe through a narrow drain line. A unit working hard on a humid Dubai summer day can produce several litres of water a day, so the drain is in use for months without a break. Water on the floor, a stain on the ceiling or drips from the front of a split unit all mean the same thing: that water is no longer reaching the drain.
What to do in the first ten minutes
- Switch the unit off at the remote or thermostat. If water is close to a light fitting, socket or the unit's wiring, switch it off at the breaker too.
- Catch and dry the water. Put a bucket or towels under the drip and move rugs, furniture and electronics. Marble, wood flooring and joinery mark quickly.
- Look at the filter. If it is grey with dust, wash or replace it. A blocked filter is one cause you can fix yourself.
- Look for ice. Frost or ice on the coil or on the copper pipes means the unit has been freezing. Leave it off to thaw fully before anyone tests it.
- Take a photo of where the water is coming from. It helps a technician bring the right parts the first time.
The common causes, and what each one looks like
| Blocked drain line | The most common cause. Dust and algae form a sludge that plugs the narrow pipe, the tray fills and overflows. Water drips steadily from the unit or appears as a ceiling stain under a ducted unit. | Technician: flush and vacuum the line. |
| Dirty air filter | Poor airflow lets the coil get too cold and ice over. When the unit cycles off, the ice melts faster than the tray can drain. Weak airflow is the usual clue. | Owner: clean or replace the filter. |
| Low refrigerant | Low pressure also freezes the coil. Signs are ice on the pipes, hissing, and a unit that runs constantly without cooling the room. | Technician: find the leak, repair it and recharge. |
| Cracked or rusted drain tray | Older units develop cracks or corrosion in the tray, so water escapes before it reaches the drain. | Technician: repair or replace the tray. |
| Unit or drain pipe not level | A split unit that tilts the wrong way, or a drain pipe without enough fall, lets water run back toward the room. Common after poor installation or renovation work. | Technician: re-level the unit and re-lay the pipe. |
| Failed drain pump | Units that cannot drain by gravity, including many ducted and cassette units, use a small pump. When it fails, the tray overflows even though the pipe is clear. | Technician: replace the pump or float switch. |
| Sweating ducts or pipes | Damaged insulation on cold pipes or ducts lets condensation form on the outside, which shows as damp patches along a ceiling rather than at the unit. | Technician: re-insulate. |
Why it happens so often in Dubai
Three things combine here. Air conditioning runs for most of the year and almost without pause in summer, so drains never dry out. Coastal humidity is highest in the hottest months, which is when each unit produces the most water. And fine dust gets into every home, settles on filters and coils, and washes into the drain tray, where it turns into the sludge that blocks the line. The same leak that takes years to develop in a mild climate can appear in a single Dubai summer if a unit has not been serviced.
Apartments connected to district cooling are not immune. Chilled-water fan coil units produce condensation in the same way and have the same trays and drain lines, and a leak there often shows first in the apartment below.
What you can safely do yourself
- Clean or replace the return-air filters, and check them monthly in summer.
- Keep supply and return grilles clear of furniture and curtains so air can move across the coil.
- Let a frozen unit thaw completely with the power off before it is tested.
- Check that the end of the drain pipe outside is not buried, kinked or blocked by debris.
Leave the rest alone. Opening the unit casing, pouring chemicals into the drain, adding refrigerant and working on drain pumps or wiring are jobs for a qualified technician. Refrigerant work in particular needs gauges and a proper leak test, and a top-up without finding the leak only delays the same fault.
When to call a technician straight away
- Water is coming through a ceiling or running down a wall
- Water is near lights, sockets or the distribution board
- There is ice on the coil or pipes, or the unit is blowing warm air
- The leak returns after you have cleaned the filter
- You can smell damp or see mould around the unit or vents
Ceiling and wall stains are worth acting on the same day. Gypsum ceilings sag and stain quickly, and water that sits above a ceiling can travel a long way from the unit before it shows. Our guide to catching small leaks early covers how to tell an AC leak from a plumbing leak.
How a technician fixes it
A proper repair starts with finding which of the causes above applies, since the water looks the same in every case. The technician checks the filter and coil, tests whether the tray drains, flushes and vacuums the drain line, tests the drain pump and float switch where fitted, and checks refrigerant pressure if the coil has been freezing. The tray and line are then treated and the unit is run to confirm water is leaving through the drain. JServices technicians explain the fault and the fix before starting, and you receive a fixed price before any work begins.
How to stop it happening again
- Monthly in summer: check filters and look for water around indoor units and stains beneath them.
- Before summer: book a full service for every unit, with coils washed and drain lines cleared. See when to service your AC in Dubai.
- After summer or a dust storm: recheck filters and drains on any unit that struggled.
- If you travel: keep the AC at a moderate setting and have someone look at the villa while you are away, so a blocked drain is not left dripping for weeks.
The full routine is in our villa maintenance checklist for Dubai. Owners who would rather not track it themselves can use a JServices annual care plan, which schedules these visits through the year.
Related services
Questions
Why is my AC leaking water inside the house?
An air conditioner removes moisture from the air, and that water should run out through a drain line. When water appears indoors, the drain is blocked, the drain tray is cracked or tilted, the drain pump has failed, or the coil has frozen and is thawing. A blocked condensate drain is the most common cause.
Is it safe to keep using an AC that is leaking water?
No. Switch the unit off until the cause is fixed. Running it keeps producing water, which can damage ceilings, joinery and flooring and can reach wiring or light fittings. If water is near electrics, switch the unit off at the breaker as well.
Why do ACs leak more in summer in Dubai?
Units run almost constantly in summer and the outside air is humid, so each unit produces far more condensation than in winter. Dust carried indoors mixes with that water and forms the sludge that blocks drain lines, which is why leaks peak between June and September.
Can I unblock an AC drain line myself?
You can clean or replace the filter and clear the visible end of the drain if it is easy to reach. Drain lines that run inside ceilings or walls, units with drain pumps, frozen coils and refrigerant problems need a technician with the right vacuum and pressure equipment.
How do I stop my AC leaking again?
Clean the filters every month in summer and have every unit serviced before the hot season, with the coil washed and the drain line flushed. Most indoor leaks come from drains and filters that were not cleaned in time.
Does JServices repair leaking AC units in Dubai?
Yes. JServices repairs split, ducted, VRF and chilled-water fan coil units in villas and apartments across Dubai, responds 24/7 and aims for same-day visits. Send a photo on WhatsApp to +971 56 198 7703 for a fixed price before work starts.
Need help?
Send a photo or a note on WhatsApp and receive a fixed price and a time slot, often the same day. Serving Emirates Hills, Palm Jumeirah, Jumeirah Golf Estates, Dubai Hills Estate and most of Dubai.
WhatsApp +971 56 198 7703info@jservices.llcUpdated 2026-10-07. Written by the JServices team. General guidance only; electrical, gas and refrigerant work should be carried out by qualified technicians.