The sensor should be as close to level as possible, at no more than a three degree angle. Mounting shims are available if your tank has a curved top.
If you have a Devan tank, mount the monitor off center. These tanks have metal in the center.
Ensure that there are no obstructions directly under your chosen mounting position such as ball cocks, inflow and outflow pipes.
The best installation spot is on the center of the tank roof. This is usually the highest point and allows a clear view to the water surface. If you have a Devan tank, mount the monitor off center. These tanks have metal in the center.
If the center of the tank is not flat, there are alternative options:
The sensor can be installed on the tanks access lid. This is not the best position as false alarms can be triggered if you happen to remove the tank lid for inspection.
As with concrete tanks, the sensor can be installed high (but off center) using the mounting shims for leveling.
Mounting high (but off center) using the mounting shims is the standard method for installation on concrete tanks. Some customers prefer replacing the inspection lid with timber to attach the sensor.