How can I turn on a water valve in Minecraft?

So a system where I can stop the flow of water and let it flow. A kind of flap, maybe. Have already tried with a trapdoor, but does not work.

I would recommend you but.

Sticky Piston + Any block of your choice + Redstone Signal = Win.

Gate 2 blocks below Redstone torch underneath left a redstone cable and at the end of it a lever when you flip the lever, the gate closes (opens at build)

Thanks, now I have it.