Vampires Vs. Aliens, Book Three — Keith B. Darrell

They came from a dying world to steal the Earth's water, a scarce resource they need to survive but didn't anticipate resistance from the vampires. The aliens' plan would doom the human race... And with no humans or other life left on Earth, the planet's furtive vampire population would be deprived of its sole food source. Now the vampires must wage a secret war against the invaders while hiding their own existence from the humans. In Book 3, Huddled Masses, reporter Pete Riley discovers the existence of both the aliens and the vampires but that knowledge may cost him his life. The aliens face the prospect of turning from invaders to refugees but will the Earth perceive them as victims or villains? New arrivals among the Hyperions initiate a conflict between church and state in the aliens' society, while newcomers to the mansion include  an Ancient vampire older than the Earth itself, and an Elder hiding a deadly secret.