I absolutely love the the hydraulic analogy, and my advancing age and the 'tism compels me to share a story.

I was a science major and worked as a tutor through college. Intermediate physics was required for all science degrees, so basic electrical theory consistently came up.

What I love about the analogy is it's actually not perfectly analogous, but the differences become obvious once the initial concepts are understood, then those differences help students figure it all out. Its imperfection is actually what makes it perfect, and my nerdy side just loves that kind of stuff.

The students that argued with me the most about how it was a shit analogy were my favorite because they'd so frequently knock it out of the park come exam time. It was like the academic equivalent of hate fucking.