Why is my aircon leaking water?

An aircon leaking water indoors is usually a drainage problem rather than a refrigerant one. In Singapore's humid climate, a split unit removes a lot of moisture from the air, and that water has to flow out through the drain tray and pipe. When the path is blocked, tilted or damaged, it overflows into the room.

Why aircon units drip in Singapore homes

Every split system produces condensate while cooling. Warm, humid air passes over the cold indoor coil, moisture condenses, and the water collects in a tray before draining away. Singapore's high humidity means this happens all day, so even a partial blockage can lead to visible dripping within hours.

Most leaks fall into a few groups. A drain pipe clogged with dust, slime or mould is the most common. Others come from a cracked tray, a pipe that has slipped or sagged, an indoor unit that is not level, or a condensate pump that has stopped working where one is fitted. Ice forming on the coil can also melt and overflow when the unit is switched off.

What you can safely check yourself

Start with the simple things you can see without tools. Switch the unit off at the remote and at the isolator before touching the front panel. Never open the electrical compartment or the outdoor unit.

• Clean or replace the washable filters, following the manual for your model.
• Check whether the indoor unit looks visibly tilted compared with the ceiling or wall line.
• Look at the drain pipe outlet outside or in the service yard, if it is visible, to see whether water is coming out.
• Note whether the leak happens all the time or only after long running.

Dirty filters reduce airflow, which can make the coil too cold and lead to icing and dripping. Cleaning them is a reasonable first step, but it rarely clears a blocked drain on its own. Do not push wires or pour chemicals into the drain line; a technician can flush it properly and check the slope.

Protect your home while you wait

Water near electrical points is a safety concern. If water is dripping close to a socket, a light or the isolator, switch off the aircon and keep the area dry. Put a towel or a container under the drip and move furniture, electronics and rugs away from the wet area.

In an HDB flat or a condo, check whether water is reaching a neighbour's unit or common areas. If the leak seems to come from a ceiling rather than your aircon, the ceiling leak guide from HDB explains how responsibility is shared, and the leak repair guide covers plumbing leaks.

What a technician will do

A servicing visit for a leak usually includes flushing or vacuuming the drain pipe, cleaning the tray and checking the flow. Many companies include drain clearing as part of general servicing, so ask whether a standard service covers your problem before booking a separate repair. The servicing price guide shows typical service scopes.

If the drain is clear but the leak continues, the technician should check the installation. Common findings include a pipe that rises before falling, a unit mounted out of level, damaged insulation that lets the pipe sweat, or a cracked tray. These can need re-installation work, which costs more than a clean. Ask for the finding to be explained, ideally with a photo.

Where water keeps dripping after the unit stops, the technician may check airflow and the refrigerant level. Ice on the coil is often linked to low airflow or low gas. The aircon repair guide covers gas leaks and other repairs in more detail.

Ask before you book

A short message with the right details saves a wasted trip and helps you compare quotes. Tell the company which unit leaks, how long it has been happening, when it was last serviced and whether the unit is still cooling. Photos of the indoor unit and the wet area help.

• Does general servicing include clearing the drain pipe?
• Is there a separate charge for a pump, tray or pipe repair?
• What happens if the leak is caused by the original installation?
• Is there a warranty on the work if the leak returns soon after?

Published rates from directory companies for leak and drain work appear below where they are available. They are each company's own advertised rate, so check the source for minimums and conditions.

Preventing future leaks

Regular servicing keeps the drain path clear. How often depends on how much you use the unit, the dust level in your home and the manufacturer's guidance. Ask your technician to recommend an interval after seeing the condition of the drain and coil, rather than relying on a fixed schedule.

Keep filters clean between visits and avoid running the unit with windows open, which pulls more humid air through the coil. If the same unit leaks repeatedly, ask the company to check the installation rather than only clearing the drain each time.

Aircon leaking water questions

Is it safe to keep using an aircon that is leaking water?

Switch it off if water is near a socket, light or the isolator, or if it is spreading quickly. A small drip into a container away from electrical points is less urgent, but book servicing soon to avoid damage to the wall, ceiling or floor.

Will general servicing fix a dripping aircon?

Often, if the cause is a blocked drain pipe or a dirty tray. Ask the company whether its servicing includes flushing the drain. If the leak continues afterwards, the installation or another part may need checking.

Why does my aircon drip only after I switch it off?

Ice can form on the coil when airflow is poor or the gas level is low. When the unit stops, the ice melts and can overflow the tray. Clean the filters and ask a technician to check airflow and refrigerant.

Who pays if my aircon water leaks into my neighbour's flat?

Responsibility depends on the cause and the circumstances. Stop the leak first, talk to your neighbour and keep records of the repair. For leaks from ceilings or shared pipes, check the HDB or management guidance before arranging work.