The most important thing is done, the horizon is leveled, all that's left is the minor details. A water level helped me with this. What is a water level, simply put? A water level is a special tool, a device used to level a horizontal plane. In this video, I explain how to use a water level alone. How does a water level work? A water level is filled with water and works using communicating vessels. The most important thing is to keep the hose free of air bubbles and locks, otherwise the level will read incorrectly. Water level hoses can vary in length; my water level hose is short, so I had to drive pegs in at the appropriate distance to move the marks from one post to the next.