What's the worst part about an EMP attack?

The weapon in question: Boeing's "CHAMP," short for Counter-electronics High-powered Microwave Advanced Missile Project. It's essentially the old nuclear electromagnetic pulse weapon that we used to worry so much about -- but without the nuclear part. CHAMP carries a small generator that emits microwaves to fry electronics with pinpoint accuracy. It targets not nations or cities but individual buildings, blacking out their electronics rather than blowing up physical targets (or people).

the worst part being 70% of the US population dead in 100 days.

With no water in a few days, fires everywhere, and people pooping outside, probably 90% or more would die in a week or two.

I don't see anyone surviving it. Survive when there are dead, dehydrated bodies everywhere?

There are ways. Having water stored until you can restore a supply, having an alternate way to pump water, having seeds and having a garden set up. Not being in a place where a fire in one house will adversely affect my own. Being able to have an open flame without it becoming out of control.

Yeah, it's asking a lot but I could do it tomorrow.