Name of a book? Storyline similar to the Movie "The Faculty".

I happened to catch the movie "The Faculty"recently. As I was watching it, I felt that the storyline was very familiar.

I remember reading a book back in either middle school or highschool. I was reading it for fun, I’m sure it wasn’t assigned. It was quite similar to that movie. Basically, it was about aliens getting into the water system and turning people into monsters. It started with the football team since they drank the most water.

I dont’ remember many particulars. I do know that the heroine of the story ended up blowing up a house that was on the water during a party to take out the aliens. And she herself turned into an alien, but somehow retained enough humanity to only feed on deer and wildlife - and not eat humans.

Anyone know what book I’m talking about?

Here’s my one bump.

I’ll try and describe the book a bit more. Lets see…

If you drink the water, you gradually turn into the alien form. You end up looking kinda like a gargoyle with leathery wings - and I think you’re purple.

The scene where the monster get blown up at the end - the bombs are big water jugs (the type that go on water coolers or bubblers) filled with gasoline. I remember them going into some detail about not filling the jugs all the way with gasoline, because it’s the vapors that ignite - not the liquid.

While the heroine was trying to set up the bombs, one of the monsters gets shot in the gut with a 12 gauge shotgun. It blows a hole straight through him, but doesn’t slow him down.

Anyone read this book? I know it’s kinda a long shot.