The operation of the ejector technology is shown in the figure. The suction effect of the water-jet vacuum pump is based on the Bernoulli principle of negative pressure. Vacuum is created in the front part of the ejector (left branch in the figure), by which the solid-liquid-mixture that is backed up in the manhole is sucked in. This process is supported by adding water under pressure via a laterally installed pressure line (lower branch in the figure).