Survival bunkers are shelters buried underground that are designed to be able to withstand catastrophic events. Most bunkers are buried at least 20 feet deep and provide air filtration systems. Survival bunkers can be homemade or purchased and installed professionally.
Professional bunkers typically come with water and air filtration, sanitation, cooking methods and communications equipment. Bunkers are typically made of steel. Companies that provide bunkers also typically offer classes to ensure clients have basic knowledge of first aid, fire starting and self-defense. High-end bunkers come with bank-vault-style doors, and they are able to withstand a nuclear, biological or chemical attack, or a natural disaster.