Why must an electrical circuit be closed for energy to flow?

The electrical circuit is analogus to the water piping system. The Word "close" means connection of a switch to get a complete circuit and to a water system you open the valve to let the water flows. Likewise if there is a connection the electrical energy flows. If "open" that means disconnected and for water piping system closing the valve to stop water flows. Therefore "close" for electrical ciruit means "open" for water piping system, and "open" for the former means "close" for the latter.