Air Coolers and Mosquito Breeding: A Cleaning Routine

Desert and evaporative air coolers are everywhere in Bangalore's summers. They keep rooms comfortable, but their water tanks hold exactly what Aedes mosquitoes want: small amounts of still, clean water, in a shaded spot. A neglected cooler can produce a crop of mosquitoes within a week.

This guide gives a simple cleaning routine.

The short answer

Air coolers breed mosquitoes when water stays in the tank or tray for several days, especially when the cooler is not running. To prevent this, empty the tank and tray completely at least every few days, scrub the sides and corners to remove stuck eggs, rinse and dry, refill with fresh water, keep the lid or cover closed, and never leave water in a cooler that is out of use. Clean pads and filters regularly, and drain and dry the cooler fully before storing it. Check the room for mosquitoes, and look for larvae in the water.

Why coolers are risky

• The tank holds still water for long periods.
• Many are placed in shaded corners or on balconies.
• Water topped up without emptying lets larvae develop.
• Idle coolers can sit with stagnant water for weeks.
• Aedes eggs stick to the tank walls and survive drying.

Cleaning routine

1. Switch off and unplug the cooler.
2. Drain the tank and tray fully.
3. Scrub the sides, corners, float and the waterline with a brush and a little detergent. This removes eggs.
4. Rinse well and dry in the sun if possible.
5. Clean or replace pads and filters as the manufacturer advises.
6. Refill with fresh water.
7. Check for larvae with a torch each time you refill.

Do this every few days in hot weather, and at least weekly.

During use

• Keep the lid and covers closed so that mosquitoes cannot lay eggs.
• Do not just top up water. Change it.
• Keep the cooler's surroundings dry, and wipe spills.

When the cooler is not in use

• Drain it completely, scrub and dry it.
• Store it with the lid on or covered, upside down if possible.
• Do not leave water in the tank or tray.

Other cooling water to check

• Desert cooler trays and overflow channels.
• Water dispensers and their trays.
• AC trays and drain lines.

If you find larvae

Drain into a drain, scrub thoroughly, dry and refill. Check other containers around the home.

Health note

Dengue and chikungunya mosquitoes bite in the day, including indoors. See a doctor if you develop fever, severe headache, joint pain or rash.

When to call a professional

If mosquitoes persist indoors, a professional can find other breeding sites.

Frequently asked questions

How often should I change cooler water?

Every few days.

Can I add something to the water to stop larvae?

Do not add chemicals. Regular cleaning works better.

Do coolers breed mosquitoes when running?

They can, if water stands and eggs are laid.

Are ACs better?

They have trays and drain lines that need checking too.

This guide is part of IPest's complete resource on mosquito control. For identification help, prevention and treatment options, see our full mosquito control guide for Bangalore.