How to prevent cockroaches from infesting your drains:

1. Keep counters and appliances clean. Don’t leave food on the counters or in the kitchen sink, especially overnight.
2. Cover drains with a stopper at night. You can use rubber drain covers or metal drain screens. Cockroaches are nocturnal, so it’s most important to block their entry at night.
3. Clean your kitchen drain. Rinse your kitchen drain with an approved kitchen sink cleaner to remove food particles that attract roaches.
4. Move or remove the garbage cans. The garbage cans under your kitchen or      bathroom sink can attract roaches.
5. Use roach monitors (“sticky traps”) to locate roaches. It may not be the most pleasant of tasks, but monitor what kind of roaches your traps catch. This can help you understand where they're coming from. Note:

1. Baby cockroaches usually stay within two feet of their hiding places.
2. Adults usually stay within about 10 feet of their hiding places.

Use bait or insecticide to kill cockroaches. Do NOT use sprays, foggers or bombs. In addition to safety concerns, they repel the roaches, causing them to avoid the insecticide, and may cause the cockroaches to scatter to other areas.

How to eliminate cockroaches' water sources and entry points:

• Cease the condensation. Wrap insulation foam and tape around any pipes that produce condensation. When you remove their water source, the roaches will go elsewhere for water.
• Seal crevices and holes around your drain pipes. You can use duct tape as a quick fix for cracks and crevices. For a longer-term solution, use silicone caulk, plaster or cement.
• Fix leaky faucets. Standing water attracts cockroaches. Seal crevices and holes around your drain pipes with caulk, plaster or cement.
• Address holes in your walls. Use expanding insulation foam to seal any spaces around the pipes where they come through the walls.
• Seal your drain pipes. Use a flashlight to locate any cracks or holes in your drain pipes. If you find cracks or holes, seal them with appropriate caulk.
• Look for gaps around the pipes under your sink. Fill these gaps with silicone sealant or urethane foam. You can fill larger holes with steel wool or copper mesh before you seal them.

Methods of killing cockroaches in your drains

Use boric acid to kill the cockroaches. Boric acid, a white powder available at hardware or home improvement stores, can be an effective tool against roaches in your drains when used correctly. Be sure to follow the directions on the label for appropriate use. While it's lower in toxicity than other insecticides, you still want to keep boric acid away from children and pets. Replace the mixture every two weeks.

Use diatomaceous earth to kill cockroaches. Sprinkle it underneath your sink, in cupboards or along baseboards to kill cockroaches. Diatomaceous earth is not poisonous but you should still exercise caution when using around pets and children.