NBC Decontamination Field Guide FM3-5
To survive a nuke-bio-chem environment you've got know how to clean up afterwards
This manual is extremely useful despite listing a lot of specific U.S. military gear in procedures. Much of it is available in surplus channels and the rest are easily substituted with civilian counterparts. Super Tropical Bleach is sold commercially as pool bleach and can be mixed to matching concentrations in the manual.
The coming 5th generation wars will be apocalyptic and Klausewitzian. It is good policy to assume that you should never skip decontamination with what might be at stake. You could drag a biological contagion into your group that might be fatal to everyone within a week. Horrible lesions could appear on inhabitants of your shelter from chemical weapons on undecontaminated clothing. A few radioactive particles could be on your gear that get inhaled by somebody into their lungs and becomes a death sentence. Never skip the staging area prep and decon and always change all gear and clothing when exiting or entering.
If you have one fixed shower head in your shelter, it should be in the staging area for this reason. Remember as always it is the little neglected details that get you.
Regards, Tex