As you need around 10 square feet per person, this would give you a bunker big enough to house up to six people.

The most popular 1,500-gallon septic tank measures around six feet wide by 10 feet wide, giving you approximately 60 square feet of floor space. If your septic tank is already trapping and filtering your toilet waste, you can’t go and live in it, but you could install another one as your purpose-built backyard bunker. Underground Bunker Plans #1 Septic Tank DesignĪ concrete septic tank makes a sturdy base for a basic underground shelter and is cheap and comparatively quick to install.Īround 20% of all the homes in the US already have a septic tank installed, but that doesn’t help. There aren’t a lot of underground bunker plans available for free, but you can get some useful ideas from companies manufacturing bunkers or using the plans for old bomb shelters and root cellars as a basis for your design. Designing and building your own is a cheaper option and one you can achieve relatively easily, provided you can come up with some viable plans. As climate change and global unrest promise more local and global catastrophes so, more people are considering having a subterranean world to escape to.Īlthough you can buy ready-made underground bunkers, these are often prohibitively expensive.

How to build a nuclear fallout shelter