Why there was a garden hose on the roof, Frank wasn’t sure, but every time the giants sent up a cannonball, Percy summoned a high-powered blast of water and detonated the sphere in midair. Then Frank remembered—his family was descended from Poseidon, too. Grandmother had said their house had been attacked before. Maybe they had put a hose up here for just that reason.

The Son of Neptune, Chapter XXXVI