Water part for a piston pump, in particular of a piston pump functioning as a flush pump

A fluid end module (12) for attachment to a piston pump (10), wherein the fluid end module (12) incorporates a support unit (14) that can be releasably attached to the piston pump (10) and at least one suction module (16) and pressure module (18) that are releasably connected or can be releasably connected to the support unit (14),

• wherein the support unit (14) and the/each suction module (16) as well as the/each pressure module (18) are of such an embodiment that the suction and pressure modules (16, 18) are interchangeable with one another,
• wherein each suction module and pressure module (16, 18) has at least two planned lateral faces, one of which functions as a lower connection face and one—adjoining the lower connection face—functions as a lateral connection face, and
• wherein a channel (26) inside the respective suction module and pressure module (16, 18), which can be blocked and released by means of a valve (34) which is incorporated by the respective suction module and pressure module (16, 18), terminates on one side in the lower connection face and on the other side in the lateral connection face.