Last year, I decided to do a Minecraft hi-tech house, with some new, never seen things, so, I decided to start with a bathroom, and, of course, a toilet. This is a great thing to show to your friends. It has regular water, and, if it's really bad, disinfectant (lava), wich I only reccommend in those cases, becouse lava takes forever going out. It's really easy to make. It takes some space, but you also get a sink (water in the wall that doesn't fall). Maybe, if this idea works, in the next minecraft update there is a toilet. So, let's get started.
Step 1: The Digging
First, dig a 4x3x1 hole, and then a cross like the one in the image, the sides 2 squares deep and the center 3 squares deep. This cross will be the sewer.
Step 2: The Toilet and the Sewer
To do the sewer fill the cross's sides an put a square in the bottom of the sewer, then cover it with more cubes. Now for the mechanism make a wall like the one in the image and put a cube in the middle of the hole, one cube above, like in the image, count three squares and place a sticky piston faced towards the middle on each side. in front of the pistons now place a cube, to make the valve. Now make a tank like in the image. Don't fill it now! You can only fill it after the wiring is done.
Step 3: The Wiring
The wiring is very simple. First you make a wall to hide the mechanisms and then:
THE WATER WIRING:
For the water wiring, you put a button in the wall, reverse the signal and plug it to the water piston.
THE LAVA WIRING:
The lava wiring is very simple, as it is slower, a button doesn't work, so we use a lever plugged directly to the piston.
Step 4: Decoration
I have placed some message boards in the walls a trapdoor for the toilet's lid and the sinks. The sinks are made by placing a message bord on the wall's corner and remove that corner's cube, allowing the water to flow in. see the images if you don't understand.