The water manometers VA and VD series are used for accurate adjustment of vacuum values in the suction in interventions of gastric and chest drainage. The devices are made essentially of a cylinder head manufactured in anodized aluminum in which a needle valve acts for suction rate adjustments, and where a primary polycarbonate tube containing the water gets the function of measurement and calibration. Inside the tube, a graduated dipstick having scale up to 40 cm (VA/600 and VD/600) or up to 70 cm (VA/1000 and VD/1000) is used to adjust the hydraulic head necessary for the treatment. The VD series has also a secondary tube for fine adjustment of hydraulic head values, and, consequently, of the suction value, up to a maximum value of 5 cm.