Ants in the Bathroom: Moisture and Drain Causes

A line of ants crossing the bathroom floor, or small ants around the sink and drain, is a common sight in Indian homes. There is usually no food in the bathroom, so what brings them? Almost always, it is water, and sometimes a nest in the walls nearby.

This guide explains the causes and the fixes.

The short answer

Ants come into bathrooms for moisture, especially during dry weather when they seek water, and use pipes, wall voids and drains as routes. Leaking taps and pipes, damp walls, wet floors, clogged drains and soap residue attract them, and some species nest in damp walls or behind tiles. To stop them, fix leaks, keep the bathroom dry, clean drains, seal gaps around pipes and tiles, find the entry trail and treat the nest with bait, and use ventilation. Sealing and drying matter more than spraying.

Why bathrooms attract ants

• Water: Leaks, drips, wet floors and damp corners.
• Drains: Organic residue, soap scum and hair.
• Warmth and humidity: Attractive to some species.
• Hidden routes: Pipes and wall voids connecting to other rooms.
• Nests: Behind tiles, in damp walls or in nearby plants.

Where to look

1. Around the sink, basin and toilet pipes.
2. Floor drains and the gap around them.
3. Shower area, tile joints and the base of walls.
4. Behind the toilet cistern and under cabinets.
5. Windows and ventilators.
6. Buckets and storage containers with water.

How to fix it

• Repair leaks: Dripping taps, pipe joints and cisterns.
• Dry up: Wipe wet floors and surfaces, and ventilate or use an exhaust.
• Clean drains: Clear hair and debris and flush with water. Keep covers in place.
• Seal gaps: Close cracks around pipes, tiles and the floor-wall joint with suitable sealant.
• Follow the trail: Find where ants enter and where they go.
• Use bait: Place gel bait near the trail, away from water spray and out of reach of children and pets, so that workers carry it to the nest.
• Remove water containers that sit for long periods.

Drains and plumbing

If ants seem to emerge from the drain or from behind tiles, there may be a nest in the wall or a damaged pipe or sealing. A plumber and a pest controller may both be needed.

Prevention

• Keep the bathroom dry and well ventilated.
• Wash the floor and drains regularly.
• Check for leaks monthly.
• Seal gaps when renovating.

What not to do

• Do not use strong chemicals in closed bathrooms without ventilation.
• Do not rely on sprays that kill only the visible ants.

When to call a professional

If ants return despite drying and sealing, call a professional to trace the nest and treat safely.

Frequently asked questions

Why are there ants in my bathroom but no food?

They are likely looking for water.

Do ants nest in bathroom walls?

Some species do, in damp walls.

Are bathroom ants harmful?

Mostly a nuisance, but they can contaminate surfaces.

Will bleach stop them?

It may remove trails, but does not solve the cause.

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