These low pressure water jet pumps achieve the theoretical ultimate vacuum at a water pressure of only 0.5 bar. The vacuum does not collapse even when the operating water pressure drops. There is no interference when water is discharged from a neighboring tapping point. Water jet pumps from Thermo Scientific enable operation without back-pressure. If the water pressure drops below 0.4 bar, the water flows back into the intake socket of the pump and closes the built-in check valve.