Things You'll Need
Instructions
Flatten a workspace at least six blocks wide by five blocks long. More room might be helpful to move around the sides of the build.
Arrange your sticky pistons on the ground facing upward in a group two blocks wide by three blocks long.
Place your redstone repeaters alongside the pistons. You will need three per side, each touching and pointing directly at its own piston.
Lay out your redstone dust in a horseshoe pattern around what you have built already. Every redstone repeater should be connected together via a continuous line of dust.
Place your lever on the ground next to the redstone dust horseshoe. It needs to be directly adjacent to the dust to function. At this point you can test the mechanism to see if you have connected things properly. Pulling the lever should raise all six pistons together.
Return your pistons to the down position and place a block of dirt on each of them. This will be the bottom of your pool. Build out from these blocks to create a bowl shape above your bridge mechanism; then fill it with water. This final step is optional, but will demonstrate what you can expect from a finished product.