Poor Steve. Never gets a chance to go to the bathroom. He never goes to the bathroom. But now he can! Thanks to you! Now Steve will be able to flush! Yay!

Step 1:

everything but the map
water
redstone
redstone torch
sticky piston

Step 2:

build a 2*3 hole and tall enough for you to stand in then in the long section, dig 3 holes across again and 1 hole down as shown in picture 3

Step 3: Wiring

put water in the 3*1 hole you dug in step 2. in the middle block next to the water, put a piston as shown. Add a lever by your toilet hole. Then put a redstone torch on the back of Tue same block as the lever and turn the lever off. Then add redstone under the torch.