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CausesModerate risk

Why Are Cockroaches in My Bathroom?

Written by PestMan Editorial TeamTechnical review pendingPublished Updated

Quick answer

Bathrooms give cockroaches water, warmth and hiding places, and they are connected to the drains. Large cockroaches often come up through floor wastes or shower drains whose water traps have dried out, while small German cockroaches shelter in vanity cupboards and around pipes. Keeping drain traps full, fixing leaks and sealing gaps around pipes removes most of the attraction.

Why this happens

Cockroaches need water more than food, and a bathroom provides it every day: wet floors, condensation, dripping taps, slow leaks under the vanity and damp towels. Bathrooms are also warm and full of gaps around pipes and fittings, which make ideal hiding places.

Bathrooms connect directly to the sewer and stormwater system. Every floor waste, shower drain and basin has a water-filled trap that blocks drain odours and insects. In spare bathrooms and laundries that are rarely used, the water evaporates and large cockroaches can climb straight up from the drain. See can cockroaches come through drains.

Small cockroaches that stay in the bathroom, especially in apartments, are often German cockroaches spreading from the kitchen or from a neighbouring unit through shared plumbing. They feed on soap residue, toothpaste, hair and skin flakes as well as crumbs. See can pests move between apartments.

What you may be seeing

  • A large reddish-brown cockroach near the shower or floor waste, usually at night: probably an American cockroach coming from the drains.
  • Small light-brown cockroaches in the vanity cupboard or around the hot water pipes: possibly German cockroaches breeding indoors.
  • Droppings like ground pepper or coffee grounds in cupboard corners and along pipe gaps.
  • A musty smell in cupboards under the basin.

What you can do

  • Run water into every floor waste, shower and basin at least weekly, especially in spare bathrooms and laundries.
  • Check drain grates are in place and undamaged, and replace any that are missing.
  • Fix dripping taps and leaks under the vanity, and dry wet floors.
  • Improve ventilation with the exhaust fan or an open window after showers.
  • Seal gaps where pipes enter walls and floors, and around the back of the vanity.
  • Clear clutter from under the basin and store products in sealed containers.
  • If you see small cockroaches, also check the kitchen, which is usually where they breed.

What not to do

  • Do not pour insecticides or strong chemicals down drains; it is harmful to waterways and doesn’t fix a dry trap.
  • Do not ignore a persistent sewer smell, which can mean a dry or faulty trap that a plumber should check.
Using pest products safely

If you use any insecticide or bait, read the label first and follow it exactly. Australian law requires products to be used only as the label directs, including where and how they may be applied and how to protect children and pets.

When professional help may be needed

An occasional large cockroach from a drain is usually solved by keeping traps full and grates in place. Consider a pest manager if small cockroaches or nymphs keep appearing, and a licensed plumber if traps keep drying out, drains smell or a grate is broken.

Cockroaches

Fast, flat-bodied insects that hide in warm, damp gaps and come out at night to feed. A few introduced species cause most household problems in Australia.

Species mentioned

American Cockroach

Periplaneta americana

One of the largest household cockroaches in Australia. Lives in drains, sewers and sub-floors and wanders inside on warm nights.

German Cockroach

Blattella germanica

A small, light-brown cockroach that lives and breeds indoors, mostly in kitchens and bathrooms. It reproduces faster than any other household cockroach and is the species most often behind persistent indoor infestations.

Guide

The Australian Guide to Cockroaches

Everything an Australian household needs to know about cockroaches: which species you are seeing, why they are there, how they get in, the health implications, and how to prevent and manage them.

Guide

How to Pest-Proof Your Home

A practical, room-by-room approach to reducing pests without relying on chemicals: remove what attracts them, close the ways in, and make your property less comfortable for them.

Guide

Common Brisbane Household Pests

A Brisbane-specific overview of the pests residents meet most often, when they are active, and what the subtropical climate, storms, creeks and Queenslander homes mean for pest pressure.

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Sources & further reading

PestMan provides general information only and does not replace licensed pest-management, medical, veterinary or structural advice. Always read and follow product labels. Read our disclaimer.