Tips for building your own fallout shelter
The main purpose of a fallout shelter is protect you from
the fallout radiation from a nuclear blast. The following
amounts of material will protect you from 99% of the
radiation:
You'll need one gallon of water per person per day. You'll need
to be underground for at least 14 days.
Source: Canadian Department of National Defence,
11 Steps to Survival, 1969.