Cockroaches in the Bathroom, Not the Kitchen

The species

This Is Almost Always Oriental

People expect cockroaches in a kitchen because German cockroaches are in kitchens. If yours are in a bathroom, a cellar or a ground-floor hallway, and they are large and very dark rather than small and tan, you are almost certainly dealing with an Oriental cockroach — and that changes where the problem actually is.

Orientals want cool and damp, not warm and dry. A bathroom, a cellar, a utility room, the void under a suspended ground floor and the drainage around a building are all better habitat for them than a kitchen.

Why the bath

They Can Get In and Cannot Get Out

Finding one in the bath or a sink is so common it is almost diagnostic, and the reason is mechanical rather than behavioural.

Oriental cockroaches climb rough surfaces perfectly well but cannot get purchase on smooth vertical ones. So an individual that comes up a waste pipe or wanders across a floor and drops into a bath is then stuck in it, still there in the morning, in plain sight.

It also means the bath is where you find them rather than where they live. The living is happening somewhere lower and damper.

Where it is coming from

Look Outside and Below

For an Oriental problem the source is frequently not inside the house at all. Worth checking:

• Drains and gullies, particularly an open or damaged gully at the back of the property, and any manhole with a cracked or ill-fitting cover.
• The void under a suspended ground floor, via airbricks.
• Waste pipe entries where they pass through an external wall, and unsealed soil stack boxing.
• Cellars and coal holes, and any below-ground light well.
• Outbuildings, compost and stacked material against the house, which is where they live outdoors in summer.
• Shared drainage in a terrace, which is a route between properties.

The seasonal pattern fits this: Oriental problems indoors tend to increase as autumn arrives and the outdoor population pushes in.

What helps

Water, Gaps and Drains

Because the driver is damp rather than food, the useful interventions are different from a kitchen job.

Fix leaks and reduce standing water. Ventilate the bathroom properly. Make sure gullies are clear, intact and correctly covered. Seal where waste pipes pass through walls. Mesh airbricks — the same work that keeps rodents out. Move stacked material and compost away from the wall.

Treatment follows the same logic: it goes to the drains, the gullies, the perimeter and the floor void rather than into the kitchen units. Treating the kitchen for an Oriental problem that is living in a drain is the most common way to spend money on this and get nowhere.

Short answers

Cockroach Questions

Going further

Cockroach Guides