Reservoir type water levels consist of a reservoir and tubing or hose. The reservoir is filled with water and allowed to flow through the tubing. The end of the tubing is then raised up and the water is allowed to settle after which you will have a level line. The advantages are a stable reservoir which provides a stable level line, easy one man operation, less concern about water spillage, and it's easier to move about (by pinching of end of tubing). The main disadvantage is that these provide a level line but no measurements. The WatrLevel is a reservoir style water level but the addition of the measuring staff allows real time measurements.