The WatrLevel works on the principal that water seeks it's own level.   it is very accurate.   It is also degree-independent, unlike transits and laser levels which are degree-dependent.

The accuracy of the WatrLevel is a function of the surface area of the reservoir to the volume change in the tubing when the WatrLevel is moved from point to point.  The larger the vertical change, the more water is either drained into, or, out of the reservoir - thereby either lowering or raising the level in the reservoir.   It is this change that error margins are measured upon.  Click here to learn more.

To see the specific calculations for the WatrLevel a48 click here.

To see the specific calculations for the WatrLevel a24 click here.

To see the specific calculations for the WatrLevel a12 click here.

Vertical alignment can also be important, if the measuring staff is not vertical when read errors can occur.  To see specific information click here.