To reach this point you have made several key decisions: you’ve decided to build your own underground bomb shelter rather than purchase a prefabricated kit or hire a contractor, and you’ve decided on the best location on your property. One of the most important next steps in the planning stage is to decide on the specifics of a few bomb shelter essentials: ventilation, waste disposal, and storage for your water, food, and other indispensable supplies.
Ventilation & Air Filtration
Though an underground shelter may at first feel cool, sealing several individuals inside would swiftly cause the shelter to become unbearably hot due to the natural water vapor rising from the human body, risking heat stroke and suffocation for all trapped within. This problem is easily solved with proper ventilation. An air filtration system to help keep radioactive particles out of the fresh air being moved into the shelter is also helpful, but not as essential as basic ventilation.
Your shelter should have built in air-intake and air-exhaust pipes at opposite ends to facilitate air flow. It may, however, still be necessary to further encourage air flow through the space, particularly during warm weather. An air pump that can be operated manually to remove stale air and usher in fresh air can be made at home with relatively little fuss- the simplest solution is a Kearney air pump (KAP), a pump that has been shown to be easy enough to build in a few hours even for individuals who have never heard of it before. The pump looks like a screen with flaps attached to one side (not unlike the slats of venetian blinds), hinged at the top to allow it to swing back and forth. When a pull cord is used to pull the air pump inward and then left slack on the return swing, the flaps function as one-way valves that force air flow in one direction. The pump can also have a filter attached to one side to help filter the fresh air of radioactive particles, although the filter should be removable should it obstruct too much air flow or the outside temperature rise too high.
Once you are confident that you have a reliable ventilation system in place, consider including an air-filtration system such an NBC filter. NBC stands for Nuclear, Biological, and Chemical, and it consists of 3 filters: a pre-filter for the largest particles, a HEPA filter for the finer particles, and a carbon adsorber to trap toxic chemicals. The filter should be placed over the air-intake valve.
You likely won’t be working with an extraordinarily large space as you build your shelter- the purpose, after all, is function rather than luxury. With this in mind, it is essential that you dedicate part of your space to the disposal of waste- that includes ordinary garbage from food products, as well as human waste. This consideration is significantly simpler than the issue of ventilation, but because of the sanitation issue it is essential that you are prepared for it in advance.
For the disposal of human waste, it’s simplest to plan on one or two (depending on how many people you plan to shelter) 5-gallon buckets lined with heavy trash bags and with a securely sealed lid. You may wish to keep a package of kitty litter as well, to cover the waste in layers. A portable chemical toilet such as can be found for camping/hiking is also a good choice, although you will still need to ensure that it is securely sealed and can be disposed of. Make sure there is a space in your shelter for these buckets, as far as possible from your food and water supplies, near the air-exhaust end of the shelter, and sealed as tightly as possible. For the disposal of other kinds of waste, heavy-duty trash bags should be fine. Keep the issue of space in mind as you stock your supplies, and endeavor to produce as little trash as possible.
How long you anticipate staying in your shelter will determine the quantity of supplies you keep stocked; the general rule of thumb begins with 72 hours, followed by two weeks and then up to at least 3 months’ worth of food and water. Naturally, water is the more essential of the two. Plan to store your water in the largest containers possible, both to maximize space and reduce waste (don’t bother with 16 or 20 oz plastic water bottles). Simple shelving will be adequate for food storage, though you may want to consider plastic sheeting to protect your food stores from fallout particles. Also take into consideration the potential dampness of the shelter if it is underground, and how this may affect containers made of paper/cardboard. Also plan for the necessity of pest control.