The answer to 'how to prevent cockroach' is to take a comprehensive approach that includes sealing entry points, eliminating food sources, and using targeted treatments. Start by thoroughly inspecting your home for any cracks, crevices, or other potential entry points where cockroaches can get in, and seal them with caulk or other appropriate sealants. Remove any sources of food by keeping your kitchen clean, storing food in airtight containers, and promptly cleaning up spills and crumbs. You can also use boric acid, diatomaceous earth, or other EPA-approved pesticides in targeted areas to help eliminate existing cockroach populations and deter future infestations.
If you continue to struggle with a persistent cockroach problem, it may be best to call in a professional pest control technician who can assess the situation and develop a customized treatment plan to effectively address the issue.