About forty minutes into The Crazies, the source of all the craziness is revealed to be a military cover-up gone wrong involving a secret chemical virus that was being transported to a secret government facility for destruction when the plane carrying the substance lost control and crashed into a small-town river. The river is the town's water supply and so folks that drink the water get infected and, well, they go crazy. It's a shitty explanation that was completely unnecessary, and I knew it at the time, but I was totally willing to go along with it... for a while. Why? Because the first forty minutes of the film are kind of great, especially for a genre film like this. There are two or three sequences that were really intense, making creepy use of small-town fixtures, like farm tools and little league baseball. But when the top-secret military guys come in with high-tech equipment, the craziness turns to banality, and the film rolls out the cliches. That's when characters start to do extraordinary things, like breaking into the heavily-guarded hazmat containment area just in time to save the sheriff's wife, who is tied to a bed waiting to die by the hand of the guy who is dragging the pitchfork across the floor, or when the sheriff's wife, who is pregnant, is able to beat up a guy twice her size, or when the gunshot killing the sacrificial trusty sidekick is able to be heard by the main characters a mile away for maximum dramatic effect.
Why does every film with a premise like this have to have an explanation? And sorry, but "Because it was in the original" is not an acceptable answer. Is anybody going to see The Crazies for a plot? It's a rhetorical question, but I'll answer it for you: Nope. And if there really has to be an explanation for some reason, why always the half-assed government cover-up? It's boring, and it drags a film like this down, way down.
Overall it's actually a competently made genre film, but maybe that's why I don't like it. Because, for a while, it's a great genre film, but at a certain point suspension of disbelief stopped being rewarding, and I just started questioning every little thing and picking it apart, which isn't good for any film, least of all an apocalyptic horror film.