PURPOSE: To supply good drinking water as well as to lighten the extent of maintenance service by installing a detection bar on a well bottom in a suction pipe lowermost end inclusive of a jet part.

CONSTITUTION: A detection bar 9 keeping a proper distance of up to a well bottom 10 is installed in the lowermost end of a strainer 8 in a jet part 4 to be set up in the well of a deep well pump, and a holding plate 12 being broken by impact force is installed in an upper end receiving part of this detection bar 9. With this holding plate, at the time of installation, a distance from the foremost end of a suction pipe 14 is easily and surely maintainable by the detection bar 9. In addition, draining of a stagnant water in the suction pipe 14 at the time of repairs takes place in the following procedures that the suction pipe 14 is lowered in a state of removing it from pump connection and making this pipe 14 (there is stagnant water) set free, and the lowermost end of the detection bar 9 is applied to the well bottom 10, breaking the holding plate 12. With this constitution, good drinking water is suppliable and, what is more, repairing work can be lightened.