Symptoms
- Small ants near the sink, tub, or toilet base
- Ants appearing mainly at night or in humid weather
- Trail leading toward a pipe, drain, or wall gap
Likely causes
- CommonMoisture from condensation or a minor leakCertain ant species specifically seek out damp areas like bathrooms, especially in humid climates.
- CommonNest near plumbing penetrations through the wall or floorGaps around pipes under the sink or behind the toilet give easy access from outside or from within the wall.
- PossibleSmall food or organic residue in less obvious spotsSoap scum, toothpaste residue, or hair products can occasionally attract certain ants too.
What to do
- Check under the sink, around the toilet base, and near the tub for any dampness or a slow leak.
- Fix any leak found, since ants will keep returning to a moisture source as long as it's there.
- Clean and dry the bathroom thoroughly, paying attention to grout, drain areas, and under fixtures.
- Seal gaps around pipes under the sink and behind the toilet with caulk.
- Run the exhaust fan more often to reduce humidity, which also helps prevent mold as a bonus.
- Use ant bait near the trail rather than spray so the colony, not just visible ants, is affected.
- Call a pest control professional if the ants persist, since a bathroom often connects to a wall void with an established nest.
Tools and parts
- Flashlight
- Caulk gun
Ant bait stationsSearch: “indoor ant bait stations”
When to call a pro
Call a plumber for a hidden leak, and a pest control professional if ants persist.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.