Water analogies for electronic circuits can go a long way, particularly if you don't need to model inductance, or not fully.

We can use water to explain why capacitors in series have less capacitance!

I'm now thinking whether we could build a water pressure multiplier using the cascade voltage multiplier topology.

https://en.wikipedia.org/wiki/Voltage_multiplier

Use some rubber dams or flexible pipes for the capacitors, one-way backstop valves for the diodes, and then some back-and-forth pumping mechanism to generate water AC. It should work.